|
|
|
|||||||
|
|||||||||
From the Enveloped viruses enter cells by a two-step process. The first
step involves the binding of a viral surface protein to receptors on
the plasma membrane of the host cell. After receptor binding, a
membrane fusion reaction takes place between the lipid bilayer of the
viral envelope and host cell membranes. This fusion reaction can occur
either at the plasma membrane or in acidic endosomes following
receptor-mediated endocytosis. In either case, the membrane fusion
reaction delivers the viral nucleocapsid into the host cytoplasm,
allowing the infection to proceed. Viral proteins embedded in the lipid
bilayer of the viral envelope (known variously as surface, spike, or
envelope proteins) catalyze receptor binding and membrane fusion
reactions. The critical involvement of these viral proteins in receptor
binding and membrane fusion has stimulated intensive investigation
aimed at understanding the mechanisms by which these proteins function.
In this article, we provide a brief overview of the roles envelope
(Env) (
Env Precursor Biosynthesis and Processing The Env glycoprotein of HIV-1, like those of other
retroviruses, is synthesized as a polyprotein precursor molecule which
is proteolytically processed by a host protease to generate the surface
(SU) and transmembrane (TM) subunits of the mature Env glycoprotein
complex. The unprocessed Env precursor has been designated, based on
its apparent molecular mass, gp160. The mature SU and TM Env
glycoprotein subunits are designated gp120 and gp41, respectively.
Sequence comparison of a number of HIV-1 isolates indicated that (i)
gp120 is highly variable between virus isolates and (ii) this
variability is nonuniform, leading to the designation of conserved (C)
and hypervariable (V) domains within gp120 (Fig. 1; 1-3).
A series of highly conserved Cys residues, which are involved in
intramolecular disulfide bonding crucial for achieving and maintaining
Env tertiary structure(4) , are found throughout gp120 and
gp41.
Figure 1:
Linear
representation of the structure of HIV-1 Env. Hypervariable regions (V1-V5) are indicated as cross-hatched boxes (&cjs2112;), conserved domains (C1-C5) are shown as open boxes. The amino acid positions are shown above the
bar; the arrow indicates the site of gp160 cleavage to
gp120 and gp41. Sites of glycosylation are indicated as Y, the stippled box (&cjs2108;) denotes the location of the gp41
fusion peptide, and the black bar represents the gp41
transmembrane domain.
As with other glycoproteins destined for the plasma membrane,
gp160 is synthesized on the rough endoplasmic reticulum (ER) and is
co-translationally glycosylated and inserted into the lumen of the ER.
A single stop-transfer, membrane-spanning sequence is located in the
central portion of the gp41 domain (Fig. 1; 5, 6). Shortly after
synthesis, gp160 monomers
oligomerize(7, 8, 9, 10) , a process
which is thought to be required for transport from the ER to the Golgi
complex (11) . Once in the Golgi, some of the high mannose,
ER-acquired N-linked oligosaccharide side chains are modified
to more complex forms, and gp160 is proteolytically cleaved to gp120
and gp41 (10, 12) . The HIV-1 Env glycoprotein is
extensively glycosylated; approximately half the molecular mass of
gp120 is composed of oligosaccharides(13) . All 24 potential N-linked glycosylation sites in gp120 from the HTLV-III Proteolytic cleavage of gp160 in the
Golgi is inefficient (12) and is catalyzed by a host protease
at a Lys/Arg-X-Lys/Arg-Arg motif (where X is any
amino acid) that is highly conserved among viral Env glycoprotein
precursors(16, 17, 18, 19) . Several
studies have suggested that the host enzyme responsible for cleaving
gp160 (and other viral Env precursors) is furin or a furin-like
protease(20, 21) . Other enzymes may also be capable
of mediating gp160 precursor processing, since cleavage can occur in a
furin-deficient cell line (22) , and a basic pair of amino
acids at the cleavage site is not absolutely required for gp160
processing(18) . Following gp160 cleavage, the oligomeric,
noncovalently associated gp120-gp41 complexes are transported to the
cell surface, where they are incorporated into budding virions.
Env Incorporation into Virus Particles Because of the role HIV-1 Env plays in receptor binding and
membrane fusion (see below), the virion incorporation of Env is
essential for the formation of infectious virus particles. In certain
virus systems (e.g. the alphaviruses), an interaction between
the Env protein intracytoplasmic tail and the viral capsid has been
demonstrated directly, and this interaction is required for virus
release(23, 24, 25) . In the case of
retroviruses, which do not require Env expression for virus assembly
and release (for review, see (26) ), the picture is less clear.
Evidence derived from Env and Gag mutagenesis and pseudotyping studies
has accumulated over the past decade both for and against the existence
of a specific interaction between the TM cytoplasmic tail and the
matrix protein (MA), which forms the membrane-proximal component of the
retroviral
core(27, 28, 29, 30, 31, 32, 33, 34, 35) .
In a recent study, it was demonstrated that mutations in HIV-1 MA that
blocked the virion incorporation of full-length HIV-1 Env did not
affect the incorporation of heterologous retroviral Env glycoproteins
with short cytoplasmic tails or HIV-1 Env mutants containing large
truncations in the gp41 cytoplasmic tail(36) . This latter
finding implies that the incorporation of Env glycoproteins with long
cytoplasmic tails (i.e. lentiviral Env glycoproteins) depends
upon a specific interaction between sequences in the cytoplasmic tail
of the TM glycoprotein and the HIV-1 MA, whereas the incorporation of
Env glycoproteins with short cytoplasmic tails into HIV-1 virions does
not(36) . The initial step in HIV-1 infection involves the binding of
virion-associated gp120 to the cell surface molecule CD4, which serves
as the major receptor for HIV-1 and the related HIV-2 and simian
immunodeficiency viruses (SIVs)(37, 38, 39) .
The Env determinants of CD4 binding map to gp120, in particular C3 and
C4(40, 41, 42) . CD4 binding to gp120 induces
conformational changes in both gp120 and gp41 that result in the
exposure of Env domains (see below) that are thought to be involved
directly in the membrane fusion
reaction(43, 44, 45, 46) . Following the identification of CD4 as the primary receptor for HIV,
it was determined that soluble CD4 (sCD4) could neutralize virus
infectivity(47, 48, 49, 50, 51) .
This neutralization was demonstrated to be primarily a result of an
enhanced shedding of gp120 from virions following treatment with
sCD4(52, 53, 54) . Initially, it was
suggested that the ability of sCD4 to neutralize HIV-1 might be
exploited therapeutically. Unfortunately, however, primary,
non-laboratory-adapted HIV-1 isolates are neutralized poorly by sCD4 (55, 56) , in part as a result of the relative
resistance of primary isolates to sCD4-induced gp120
shedding(57, 58, 59, 60) , thereby
diminishing the utility of sCD4 as a therapeutic agent. In fact, in
related HIV-2 and SIV systems, sCD4 has been reported to actually
enhance virus infectivity(61) . It is currently unclear what
role, if any, CD4-induced gp120 shedding plays in HIV-1 Env
function(62, 63) . In addition to binding CD4 on
the cell surface during the early phase of virus infection, HIV-1 Env
associates with CD4 intracellularly soon after gp160 synthesis in the
ER. Pulse-chase and transport inhibition studies suggested that within
approximately 30 min of synthesis, gp160 adopts a conformation suitable
for CD4 binding(64) . The association of Env and CD4 early in
the transport pathway leads to the down-regulation of CD4 expression
from the surface of Env-expressing
cells(65, 66, 67, 68) . This
decrease in the level of cell surface CD4 may reduce the ability of
Env-expressing cells to become infected with additional virions (66) , a phenomenon, described for other
retroviruses(69) , known as superinfection interference. It has
also been proposed that the association between Env and CD4 early in
the transport pathway may be cytotoxic(70, 71) . The ability to induce fusion between the lipid bilayer of the
viral envelope and host cell membranes is a central feature of Env
glycoprotein function. Env expression in an infected cell can also lead
to cell-to-cell fusion, or syncytium formation, with neighboring
CD4 The first domain
recognized as being directly involved in HIV-1 Env-induced membrane
fusion was the highly hydrophobic sequence at the amino terminus of
gp41. A number of studies involving the hemagglutinin protein of
orthomyxoviruses (i.e. influenza A) and the F protein of
paramyxoviruses had previously suggested that an analogous domain,
referred to as the fusion peptide, plays a role in the membrane fusion
function of these proteins (for reviews see Refs. 19 and 75-79).
Analysis of lentiviral Env glycoproteins indicated that single amino
acid changes in the highly hydrophobic amino termini of the HIV-1,
HIV-2, and SIV TM glycoproteins blocked Env-induced syncytium
formation(80, 81, 82, 83, 84) .
An extensive literature, reviewed
elsewhere(76, 78, 79) , details the
irreversible conformational changes in the influenza virus
hemagglutinin and paramyxovirus F proteins that lead to the exposure,
or ``activation'' of the fusion peptide. As mentioned above,
the HIV-1 Env glycoprotein also undergoes a series of conformational
changes following CD4 binding, one outcome of which is the exposure of
the gp41 fusion peptide(43) . Several fusion peptides may act
in concert to destabilize the lipid bilayer of the target membrane by
forming a ``fusion pore'' between the two
bilayers(77) . The hypothesis that Env glycoproteins behave
cooperatively to promote membrane fusion derives support from the
finding that substitutions of polar amino acids in the fusion peptide
of HIV-1 gp41 elicit a transdominant negative effect on syncytium
formation and virus infectivity (85, 86) and from
studies demonstrating a synergistic effect of high levels of sCD4 on
HIV-1 neutralization(87) . In addition to the amino-terminal
fusion peptide, other domains within gp41 have been reported to play a
role in the fusion process. Mutations in a putative leucine zipper
motif in the gp41 ectodomain (88) blocked syncytium formation
and virus infectivity without affecting Env oligomerization, transport,
processing, or CD4 binding(89, 90) ; a peptide based
on the sequence of this region also inhibited syncytium formation and
virus infection(91) . Substitution of two charged residues in
the membrane-spanning domain of gp41 also perturbed Env-induced
membrane fusion(92) . In a number of studies, deletion,
frameshift, or premature translation termination mutations were
introduced into the cytoplasmic tails of the HIV-1, HIV-2, or SIV TM
glycoproteins(40, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102) ,
which, as noted above, are unusually long compared with those of other
retroviruses. In some cases, these deletions enhanced Env-induced
membrane fusion, suggesting that sequences in the gp41 cytoplasmic tail
may modulate Env
fusogenicity(94, 96, 97, 99, 101, 102) . In gp120, primarily two regions are involved in membrane fusion. A
number of studies determined that antibodies to V3 were capable of
neutralizing virus infectivity(103-109) without affecting virus
binding to CD4(108, 109) . Mutational analyses
demonstrated that single amino acid substitutions within the HIV-1 V3
loop, and the analogous domain of HIV-2, blocked Env-induced syncytium
formation(83, 110, 111) and virus
infectivity(83, 112) . More recent studies have also
implicated the V1/V2 region in membrane fusion. Mutations within V1/V2
were reported to block syncytium formation without affecting the
gp120-gp41 interaction or CD4 binding(113) , and the transfer
of V2 sequences from syncytium-inducing Env glycoproteins conferred the
ability to induce fusion on non-syncytium-inducing Env glycoproteins (114, 115) . Consistent with a role for V1/V2 in
membrane fusion, antibodies to this region are capable of neutralizing
virus infectivity (116, 117) . It has been
postulated for a number of years that molecules other than CD4 may be
necessary for membrane fusion induced by HIV-1 Env. The following
observations suggest that factor(s) provided by human cells are
required for HIV-1 Env-induced membrane fusion: (i) expression of human
CD4 in murine cells does not confer upon them the ability to support
HIV-1 infection(39) , (ii) in a cell-fusion reaction, the
target cell must be of human origin, whereas the Env-expressing cell
can be of non-human origin(118) , and (iii) the formation of
some somatic cell hybrids between human cells and CD4-expressing
non-human cells can overcome the fusion defect observed in human
CD4-expressing non-human cells, suggesting that the inability of
CD4 An additional function of the HIV-1 Env glycoprotein is to
determine the cell-type specificity, or tissue tropism, of virus
infection. In culture, HIV-1 typically infects either cells of the
monocyte/macrophage lineage or immortalized T-cell lines, but rarely
both. Primary virus isolates obtained from infected individuals during
the early, asymptomatic phase of infection are frequently
non-syncytium-inducing and macrophage-tropic, and cells of the
monocyte/macrophage lineage are thought to be important targets for
virus infection in vivo (for review, see (13) 0).
HIV-1 isolates which are syncytium-inducing and capable of productively
infecting T-cell lines tend to arise late in infection after the onset
of AIDS-defining symptoms(131) . In fact, it has been argued
that the evolution in vivo of syncytium-inducing, T-cell
line-tropic variants may play a causal role in disease
development(74) . As would be predicted for a property
determined by Env, the block to infection in nonpermissive cells
appears to be primarily at the level of entry, presumably resulting
from a defect in membrane fusion(132, 133) .
Interestingly, both macrophage-tropic and T-cell line-tropic isolates
are capable of efficiently infecting primary human CD4 Studies conducted in a number of laboratories
have concluded that sequences within gp120 are responsible for
determining the tissue tropism of HIV-1. The V3 loop, discussed above
in the context of membrane fusion, plays a central role in tropism. The
introduction of sequences encompassing the V3 loop from
macrophage-tropic clones to T-cell line-tropic clones is able to confer
macrophage tropism upon certain T-cell line-tropic
clones(134-138). It is clear, however, that a combination of
sequences both within, and outside, V3 is required for optimal
macrophage infection. The exchange of additional sequences adjacent to
V3, particularly amino-terminal to V3, greatly enhances the ability of
chimeric viruses to infect macrophages(139, 140) . It
appears that V3 loop conformation differs between macrophage-tropic and
T-cell line-tropic Env glycoproteins(140, 141) , and
that residues both within and outside V3 influence V3 conformation (142) . The mechanism by which the V3 loop affects cell-type
tropism has not been elucidated. It has been suggested by some that a
sequence near the tip of the V3 loop serves as the target for
proteolytic cleavage, and that this V3 cleavage event activates the
membrane fusion potential of HIV-1 Env(143, 144) . It
was proposed that differences in tropism correlate with altered
sensitivity of the V3 loop to proteolytic
cleavage(141, 145) , although other investigators
failed to find a correlation between these properties(146) ,
and it has not been established that V3 cleavage plays any role in
HIV-1 infection. Another model for V3 loop function invokes the
existence of a cell-type specific, non-CD4 receptor molecule with which
the V3 loop interacts. To date, however, no such receptor has been
identified. In the discussion above, we have focused largely on the
functions of discrete domains within the HIV-1 Env glycoprotein. It is
becoming increasingly clear, however, that most Env functions require
the interaction between nonadjacent sequences within gp120 or between
gp120 and gp41. Although attempts to obtain a crystal structure of
HIV-1 Env have thus far been unsuccessful, a variety of biological,
biochemical, and immunological data have provided information about Env
interactions. In an early demonstration of the importance of Env
interactions, a debilitating mutation in C2 affecting infectivity could
be reversed by changes in C1 and V3, suggesting a functional
interaction between these domains of gp120(147) . More
recently, the analysis of a revertant obtained from a V1/V2 envelope
chimera demonstrated the existence of a functional interaction between
V1/V2 and C4(148) . The analysis of chimeras between
syncytium-inducing and non-syncytium-inducing Env glycoproteins also
support an interaction between V1/V2 and sequences near the carboxyl
terminus of gp120(114) . Several groups have used antibody
binding analyses to identify interacting regions within gp120. This
approach has provided evidence for interactions between V1/V2 and C4;
V3 and C1, C2, and C4; and C1, C2, and
C5(117, 149, 150, 151, 152, 153) .
An interaction between V3 and C4 is further supported by the
observation that treatment of gp120 with soluble CD4 (which binds C4)
enhances the binding of anti-V3 monoclonal antibodies (152) ,
and that single amino acid mutations in C4 increase binding by a
V3-specific antibody(153) . Although some of these findings may
be ascribed to indirect effects on protein folding rather than direct,
functional interactions, these studies are consistent with the concept
that while distinct domains within HIV-1 Env are involved in specific
functions, complex interactions between, and within, these domains are
essential for the full range of biological activities required for
productive infection.
Volume 270,
Number 41,
Issue of October 13, 1995 pp. 23883-23886
©1995 by The American Society for Biochemistry and Molecular Biology, Inc.
INTRODUCTION
Env Precursor Biosynthesis and Processing
Env Incorporation into Virus Particles
CD4 Binding
Membrane Fusion
Tissue Tropism
Env Interactions
FOOTNOTES
ACKNOWLEDGEMENTS
REFERENCES
)glycoproteins play in the human immunodeficiency
virus type 1 (HIV-1) life cycle.
HIV-1 isloate and at least three of the five sites in the
ectodomain of gp41 appear to be utilized (Fig. 1; 4, 14). It has
been suggested that HIV-1 Env also contains O-linked
carbohydrates(15) .
cells, a process that contributes to HIV
cytopathicity in culture and possibly in
vivo(72, 73, 74) . In addition to
domains required for gp160 proteolytic cleavage and CD4 binding
(discussed above), a number of determinants in both gp120 and gp41 have
been postulated to play a role in membrane fusion.
murine cells to support HIV infection is due to
the absence of factor(s) on murine cells, rather than the presence of a
mouse cell-specific interfering function(119-121). Although
non-CD4 molecules have been reported to serve as alternative HIV-1
receptors on CD4
cells(122) , no widely
accepted CD4 co-receptor has been identified. It was suggested by
Callebaut et al.(123) that CD26 (dipeptidyl-peptidase
IV) conferred susceptibility to HIV-1 infection upon CD4-expressing
murine (NIH 3T3) cells. A number of groups, however, failed to confirm
a role for CD26 in HIV-1 infection or syncytium
formation(124-128). Recent protease digestion data suggest that
the factor(s) provided by human cells may be
nonproteinaceous(129) .
T-lymphocytes.
)
We thank R. Willey and L. Derr for critical review of
the manuscript and our colleagues in the Laboratory of Molecular
Microbiology for helpful discussions.
©1995 by The American Society for Biochemistry and Molecular Biology, Inc.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  F. K. Yoshimura, X. Luo, X. Zhao, H. C. Gerard, and A. P. Hudson Up-regulation of a cellular protein at the translational level by a retrovirus PNAS, April 8, 2008; 105(14): 5543 - 5548. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Sato, J. Aoki, N. Misawa, E. Daikoku, K. Sano, Y. Tanaka, and Y. Koyanagi Modulation of Human Immunodeficiency Virus Type 1 Infectivity through Incorporation of Tetraspanin Proteins J. Virol., January 15, 2008; 82(2): 1021 - 1033. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. A. A. Travers, D. C. Tully, G. P. McCormack, and M. A. Fares A Study of the Coevolutionary Patterns Operating within the env Gene of the HIV-1 Group M Subtypes Mol. Biol. Evol., December 1, 2007; 24(12): 2787 - 2801. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. L. Murphy and G. N. Gaulton TR1.3 Viral Pathogenesis and Syncytium Formation Are Linked to Env-Gag Cooperation J. Virol., October 1, 2007; 81(19): 10777 - 10785. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. He, S. Liu, W. Jing, H. Lu, D. Cai, D. J. Chin, A. K. Debnath, F. Kirchhoff, and S. Jiang Conserved Residue Lys574 in the Cavity of HIV-1 Gp41 Coiled-coil Domain Is Critical for Six-helix Bundle Stability and Virus Entry J. Biol. Chem., August 31, 2007; 282(35): 25631 - 25639. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Bhattacharya, A. Repik, and P. R. Clapham Gag regulates association of human immunodeficiency virus type 1 envelope with detergent-resistant membranes. J. Virol., June 1, 2006; 80(11): 5292 - 5300. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. C. Williams Jr., J. Y. Lee, M. Cai, C. A. Bewley, and G. M. Clore Crystal Structures of the HIV-1 Inhibitory Cyanobacterial Protein MVL Free and Bound to Man3GlcNAc2: STRUCTURAL BASIS FOR SPECIFICITY AND HIGH-AFFINITY BINDING TO THE CORE PENTASACCHARIDE FROM N-LINKED OLIGOMANNOSIDE J. Biol. Chem., August 12, 2005; 280(32): 29269 - 29276. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Cheung, L. McLain, M. J. Hollier, S. A. Reading, and N. J. Dimmock Part of the C-terminal tail of the envelope gp41 transmembrane glycoprotein of human immunodeficiency virus type 1 is exposed on the surface of infected cells and is involved in virus-mediated cell fusion J. Gen. Virol., January 1, 2005; 86(1): 131 - 138. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Ye, Z. Bu, A. Vzorov, D. Taylor, R. W. Compans, and C. Yang Surface Stability and Immunogenicity of the Human Immunodeficiency Virus Envelope Glycoprotein: Role of the Cytoplasmic Domain J. Virol., December 15, 2004; 78(24): 13409 - 13419. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. Schiavoni, S. Trapp, A. C. Santarcangelo, V. Piacentini, K. Pugliese, A. Baur, and M. Federico HIV-1 Nef Enhances Both Membrane Expression and Virion Incorporation of Env Products: A MODEL FOR THE NEF-DEPENDENT INCREASE OF HIV-1 INFECTIVITY J. Biol. Chem., May 28, 2004; 279(22): 22996 - 23006. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. A. LaBonte, N. Madani, and J. Sodroski Cytolysis by CCR5-Using Human Immunodeficiency Virus Type 1 Envelope Glycoproteins Is Dependent on Membrane Fusion and Can Be Inhibited by High Levels of CD4 Expression J. Virol., June 15, 2003; 77(12): 6645 - 6659. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Louis, I. Nesheiwat, L. Chang, G. M. Clore, and C. A. Bewley Covalent Trimers of the Internal N-terminal Trimeric Coiled-coil of gp41 and Antibodies Directed against Them Are Potent Inhibitors of HIV Envelope-mediated Cell Fusion J. Biol. Chem., May 23, 2003; 278(22): 20278 - 20285. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. Kalia, S. Sarkar, P. Gupta, and R. C. Montelaro Rational Site-Directed Mutations of the LLP-1 and LLP-2 Lentivirus Lytic Peptide Domains in the Intracytoplasmic Tail of Human Immunodeficiency Virus Type 1 gp41 Indicate Common Functions in Cell-Cell Fusion but Distinct Roles in Virion Envelope Incorporation J. Virol., March 15, 2003; 77(6): 3634 - 3646. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. M. Cleveland, L. McLain, L. Cheung, T. D. Jones, M. Hollier, and N. J. Dimmock A region of the C-terminal tail of the gp41 envelope glycoprotein of human immunodeficiency virus type 1 contains a neutralizing epitope: evidence for its exposure on the surface of the virion J. Gen. Virol., March 1, 2003; 84(3): 591 - 602. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Kobayashi, A. Iida, Y. Ueda, and M. Hasegawa Pseudotyped Lentivirus Vectors Derived from Simian Immunodeficiency Virus SIVagm with Envelope Glycoproteins from Paramyxovirus J. Virol., February 15, 2003; 77(4): 2607 - 2614. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Licata, M. Simpson-Holley, N. T. Wright, Z. Han, J. Paragas, and R. N. Harty Overlapping Motifs (PTAP and PPEY) within the Ebola Virus VP40 Protein Function Independently as Late Budding Domains: Involvement of Host Proteins TSG101 and VPS-4 J. Virol., February 1, 2003; 77(3): 1812 - 1819. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. M. Vlad, S. Muller, M. Cudic, H. Paulsen, L. Otvos Jr., F.-G. Hanisch, and O. J. Finn Complex Carbohydrates Are Not Removed During Processing of Glycoproteins by Dendritic Cells: Processing of Tumor Antigen MUC1 Glycopeptides for Presentation to Major Histocompatibility Complex Class II-restricted T Cells J. Exp. Med., December 2, 2002; 196(11): 1435 - 1446. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. de Paulis, G. Florio, N. Prevete, M. Triggiani, I. Fiorentino, A. Genovese, and G. Marone HIV-1 Envelope gp41 Peptides Promote Migration of Human Fc{epsilon}RI+ Cells and Inhibit IL-13 Synthesis Through Interaction with Formyl Peptide Receptors J. Immunol., October 15, 2002; 169(8): 4559 - 4567. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Boutonnet, W. Janssens, C. Boutton, J.-L. Verschelde, L. Heyndrickx, E. Beirnaert, G. van der Groen, and I. Lasters Comparison of Predicted Scaffold-Compatible Sequence Variation in the Triple-Hairpin Structure of Human Immunodeficiency Virus Type 1 gp41 with Patient Data J. Virol., June 27, 2002; 76(15): 7595 - 7606. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Chertova, J. W. Bess Jr., B. J. Crise, R. C. Sowder II, T. M. Schaden, J. M. Hilburn, J. A. Hoxie, R. E. Benveniste, J. D. Lifson, L. E. Henderson, et al. Envelope Glycoprotein Incorporation, Not Shedding of Surface Envelope Glycoprotein (gp120/SU), Is the Primary Determinant of SU Content of Purified Human Immunodeficiency Virus Type 1 and Simian Immunodeficiency Virus J. Virol., May 3, 2002; 76(11): 5315 - 5325. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. A. Bewley, J. M. Louis, R. Ghirlando, and G. M. Clore Design of a Novel Peptide Inhibitor of HIV Fusion That Disrupts the Internal Trimeric Coiled-coil of gp41 J. Biol. Chem., April 12, 2002; 277(16): 14238 - 14245. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. T. West, S. K. Weldon, S. Wyss, X. Lin, Q. Yu, M. Thali, and E. Hunter Mutation of the Dominant Endocytosis Motif in Human Immunodeficiency Virus Type 1 gp41 Can Complement Matrix Mutations without Increasing Env Incorporation J. Virol., March 7, 2002; 76(7): 3338 - 3349. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Haddrick, C. R. Brown, R. Plishka, A. Buckler-White, V. M. Hirsch, and H. Ginsberg Biologic Studies of Chimeras of Highly and Moderately Virulent Molecular Clones of Simian Immunodeficiency Virus SIVsmPBj Suggest a Critical Role for Envelope in Acute AIDS Virus Pathogenesis J. Virol., July 15, 2001; 75(14): 6645 - 6659. [Abstract] [Full Text]
|
|
|
|
|
|
B. Labrosse, C. Treboute, A. Brelot, and M. Alizon Cooperation of the V1/V2 and V3 Domains of Human Immunodeficiency Virus Type 1 gp120 for Interaction with the CXCR4 Receptor J. Virol., June 15, 2001; 75(12): 5457 - 5464. [Abstract] [Full Text]
|
|
|
|
|
|
W. A. Banks, E. O. Freed, K. M. Wolf, S. M. Robinson, M. Franko, and V. B. Kumar Transport of Human Immunodeficiency Virus Type 1 Pseudoviruses across the Blood-Brain Barrier: Role of Envelope Proteins and Adsorptive Endocytosis J. Virol., May 15, 2001; 75(10): 4681 - 4691. [Abstract] [Full Text]
|
|
|
|
|
|
I. Rousso, M. B. Mixon, B. K. Chen, and P. S. Kim Palmitoylation of the HIV-1 envelope glycoprotein is critical for viral infectivity PNAS, November 22, 2000; (2000) 240459697. [Abstract] [Full Text]
|
|
|
|
 |
|
 B. R. O'Keefe, S. R. Shenoy, D. Xie, W. Zhang, J. M. Muschik, M. J. Currens, I. Chaiken, and M. R. Boyd Analysis of the Interaction between the HIV-Inactivating Protein Cyanovirin-N and Soluble Forms of the Envelope Glycoproteins gp120 and gp41 Mol. Pharmacol., November 1, 2000; 58(5): 982 - 992. [Abstract] [Full Text]
|
|
|
|
|
|
H. Akari, T. Fukumori, and A. Adachi Cell-Dependent Requirement of Human Immunodeficiency Virus Type 1 gp41 Cytoplasmic Tail for Env Incorporation into Virions J. Virol., May 15, 2000; 74(10): 4891 - 4893. [Abstract] [Full Text]
|
|
|
|
|
|
T. Murakami and E. O. Freed Genetic Evidence for an Interaction between Human Immunodeficiency Virus Type 1 Matrix and alpha -Helix 2 of the gp41 Cytoplasmic Tail J. Virol., April 15, 2000; 74(8): 3548 - 3554. [Abstract] [Full Text]
|
|
|
|
|
|
B. Labrosse, C. Treboute, and M. Alizon Sensitivity to a Nonpeptidic Compound (RPR103611) Blocking Human Immunodeficiency Virus Type 1 Env-Mediated Fusion Depends on Sequence and Accessibility of the gp41 Loop Region J. Virol., March 1, 2000; 74(5): 2142 - 2150. [Abstract] [Full Text]
|
|
|
|
|
|
T. Murakami and E. O. Freed The long cytoplasmic tail of gp41 is required in a cell type-dependent manner for HIV-1 envelope glycoprotein incorporation into virions PNAS, January 4, 2000; 97(1): 343 - 348. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Wanas, S. Efler, K. Ghosh, and H. P. Ghosh Mutations in the conserved carboxy-terminal hydrophobic region of glycoprotein gB affect infectivity of herpes simplex virus J. Gen. Virol., December 1, 1999; 80(12): 3189 - 3198. [Abstract] [Full Text]
|
|
|
|
|
|
A. Mirazimi, M. Mousavi-Jazi, V.-A. Sundqvist, and L. Svensson Free thiol groups are essential for infectivity of human cytomegalovirus J. Gen. Virol., November 1, 1999; 80(11): 2861 - 2865. [Abstract] [Full Text]
|
|
|
|
|
|
A. Brelot, N. Heveker, K. Adema, M. J. Hosie, B. Willett, and M. Alizon Effect of Mutations in the Second Extracellular Loop of CXCR4 on Its Utilization by Human and Feline Immunodeficiency Viruses J. Virol., April 1, 1999; 73(4): 2576 - 2586. [Abstract] [Full Text]
|
|
|
|
|
|
J.-C. Paillart and H. G. Göttlinger Opposing Effects of Human Immunodeficiency Virus Type 1 Matrix Mutations Support a Myristyl Switch Model of Gag Membrane Targeting J. Virol., April 1, 1999; 73(4): 2604 - 2612. [Abstract] [Full Text]
|
|
|
|
|
|
M. L. Penn, J.-C. Grivel, B. Schramm, M. A. Goldsmith, and L. Margolis CXCR4 utilization is sufficient to trigger CD4+ T cell depletion in HIV-1-infected human lymphoid tissue PNAS, January 19, 1999; 96(2): 663 - 668. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. E. Kiernan and E. O. Freed Cleavage of the Murine Leukemia Virus Transmembrane Env Protein by Human Immunodeficiency Virus Type 1 Protease: Transdominant Inhibition by Matrix Mutations J. Virol., December 1, 1998; 72(12): 9621 - 9627. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Labrosse, A. Brelot, N. Heveker, N. Sol, D. Schols, E. De Clercq, and M. Alizon Determinants for Sensitivity of Human Immunodeficiency Virus Coreceptor CXCR4 to the Bicyclam AMD3100 J. Virol., August 1, 1998; 72(8): 6381 - 6388. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W.-F. Liu, D. Gao, and Z.-N. Wang Expression of the Extracellular Domain of the Human Immunodeficiency Virus Type 1 Envelope Protein and Its Fusion with beta -Galactosidase in Saccharomyces cerevisiae Clin. Vaccine Immunol., July 1, 1998; 5(4): 592 - 594. [Abstract] [Full Text]
|
|
|
|
|
|
M. Boge, S. Wyss, J. S. Bonifacino, and M. Thali A Membrane-proximal Tyrosine-based Signal Mediates Internalization of the HIV-1 Envelope Glycoprotein via Interaction with the AP-2 Clathrin Adaptor J. Biol. Chem., June 19, 1998; 273(25): 15773 - 15778. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. M. Laten, A. Majumdar, and E. A. Gaucher SIRE-1, a copia/Ty1-like retroelement from soybean, encodes a retroviral envelope-like protein PNAS, June 9, 1998; 95(12): 6897 - 6902. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. L. McInerney, W. El Ahmar, B. E. Kemp, and P. Poumbourios Mutation-Directed Chemical Cross-Linking of Human Immunodeficiency Virus Type 1 gp41 Oligomers J. Virol., February 1, 1998; 72(2): 1523 - 1533. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. K. Judice, J. Y. K. Tom, W. Huang, T. Wrin, J. Vennari, C. J. Petropoulos, and R. S. McDowell Inhibition of HIV type 1 infectivity by constrained alpha -helical peptides: Implications for the viral fusion mechanism PNAS, December 9, 1997; 94(25): 13426 - 13430. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Tan, J.-h. Liu, J.-h. Wang, S. Shen, and M. Lu Atomic structure of a thermostable subdomain of HIV-1 gp41 PNAS, November 11, 1997; 94(23): 12303 - 12308. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Louis, C. A. Bewley, and G. M. Clore Design and Properties of NCCG-gp41, a Chimeric gp41 Molecule with Nanomolar HIV Fusion Inhibitory Activity J. Biol. Chem., July 27, 2001; 276(31): 29485 - 29489. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Farzan, N. Vasilieva, C. E. Schnitzler, S. Chung, J. Robinson, N. P. Gerard, C. Gerard, H. Choe, and J. Sodroski A Tyrosine-sulfated Peptide Based on the N Terminus of CCR5 Interacts with a CD4-enhanced Epitope of the HIV-1 gp120 Envelope Glycoprotein and Inhibits HIV-1 Entry J. Biol. Chem., October 20, 2000; 275(43): 33516 - 33521. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Dettenhofer and X.-F. Yu Characterization of the Biosynthesis of Human Immunodeficiency Virus Type 1 Env from Infected T-cells and the Effects of Glucose Trimming of Env on Virion Infectivity J. Biol. Chem., February 16, 2001; 276(8): 5985 - 5991. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. Rousso, M. B. Mixon, B. K. Chen, and P. S. Kim Palmitoylation of the HIV-1 envelope glycoprotein is critical for viral infectivity PNAS, December 5, 2000; 97(25): 13523 - 13525. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| All ASBMB Journals | Molecular and Cellular Proteomics |
| Journal of Lipid Research | ASBMB Today |