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From the
The complement system membrane cofactor protein (MCP) CD46
serves as a C3b/C4b inactivating factor for the protection of host
cells from autologous complement attack and as a receptor for measles
virus (MV). MCP consists of four short consensus repeats (SCR) which
are the predominant extracellular structural motif. In the present
study, we determined which of the four SCR of MCP contribute to its
function using Chinese hamster ovary cell clones expressing each SCR
deletion mutants. The results were as follows: 1) SCR1 and SCR2 are
mainly involved in MV binding and infection; 2) SCR2, SCR3, and SCR4
contribute to protect Chinese hamster ovary cells from human
alternative complement pathway-mediated cytolysis; and 3) SCR2 and SCR3
are essential for protection of host cells from the classical
complement pathway. These results on cell protective activity of the
mutants against the human classical and the alternative complement
pathways were compatible with factor I-mediated inactivation profiles
of C4b and C3b, respectively, in the fluid-phase assay using
solubilized mutants and factor I; the results were mostly consistent
with those reported by Adams et al. (Adams, E. M., Brown, M.
C., Nunge, M., Krych, M., and Atkinson, J. P.(1991) J. Immunol. 147, 3005-3011). SCR2 and SCR3 were required for C3b and C4b
inactivation, and SCR4-deleted MCP showed weak cofactor activity for
C4b cleavage but virtually no cofactor activity for C3b cleavage. The
functional domains of MCP for the three natural ligands C3b, C4b, and
MV, therefore, map to different, although partly overlapping, SCR
domains.
Human membrane cofactor protein (MCP)
Naniche et al.(12) and
Dorig et al.(13) have suggested that MCP also serves
as a receptor for measles virus (MV). MV, however, has no C3b-like
molecules on its envelope. H protein of MV is thought to act as a
ligand for target cell receptors, whereas F protein then induces
viral-cell fusion(14, 15) . Indeed, MV can infect human
and various monkey species, the tropism correlating with the expression
of MCP(13, 16) .
There are many MCP phenotypes, which
are distinguishable on SDS-PAGE (17-19). This polymorphism is
caused by alternative splicing of mRNA encoding the ST-rich and CYT
regions(17) . CHO cell clones expressing MCP variants with a
variety of ST-rich (20) or CYT domains (21) have been
reported to become permissive to MV. Thus, the MV-binding site on MCP
must be located within the SCR. The MV-binding site and its structural
relationship to the complement-binding site, therefore, remain to be
elucidated.
In the present study, we established CHO transfectants
expressing various SCR deletion mutants of MCP and mapped the
functional domains for complement regulation and MV binding.
Complement C3(28) , C4(29) ,
factor H(30) , and factor I (29) were purified from human
plasma as described previously. C3b and C4b were prepared (29, 30) and labeled with an SH reagent, N-(dimethylamino-4-methylcoumarinyl)maleimide
(DACM)(31) . The DACM-labeled C3b and C4b have been
characterized as substrates for factor I and
MCP(31, 32) . Glycosidases were obtained as follows: N-glycanase F (Boehringer Mannheim, GmbH, Mannheim, Germany),
neuraminidase (Sigma), and O-glycanase (Genzyme, Cambridge,
MA).
CHO cells were cotransfected
with vectors containing MCP cDNA (20 µg) and 1 µg of pSV2hph (a
hygromycin resistance gene vector) (34) by calcium phosphate
precipitation(35) . The transfected CHO cells were maintained
for 24 h in Ham's F-12 medium, 10% fetal calf serum, 0.06%
kanamycin, in an atmosphere of humidified 5%CO
Immunoblotting was
performed as described previously(36) . MCP and its mutants were
solubilized from transfectants (about 2
The supernatants of the infected cells were
harvested after sonication, and the MV titer was determined using Vero
cells by the standard method (12, 13).
The cell protection assay from human complement was performed with
Syncytium formation is a representative
marker for MV infection of CHO cells expressing MCP(13) . In
this study, syncytia were visualized under the light microscope and the
number of syncytia formed at each dose of MV was counted to determine
the titer of infectivity. The minimum doses of MV for syncytium
formation are shown in . The results reflected those of
the MV binding assay. These results suggested that SCR1 and SCR2 are
the domains essential for MV binding/infection.
Importance of the
SCR1 and SCR2 domains for MV infection was also supported by the
inhibition studies with anti-MCP mAb (). SCR2 was
particularly important, since SCR2-recognizing mAbs M75 and M177
blocked MV infection in both CHO transfectants and Vero cells. An
SCR3-recognizing mAb MH61 blocked MV infection in CHO transfectants,
but not Vero cells. This blocking effect may be due to steric hindrance
or a conformational change in SCR2 secondary to the binding of this mAb
to SCR3.
We studied which of the four SCR domains of MCP contribute to
the cofactor activity for factor I-mediated cleavage of C3b and C4b,
the protection of host cells from complement-mediated cytolysis, and MV
binding activity, using deletion mutants. In summary: 1) SCR1 and SCR2
are mainly involved in MV binding and infection; 2) SCR2, SCR3, and
SCR4 sustain sufficient C3b inactivation by factor I; and 3) SCR2 and
SCR3 are essential for factor I-mediated inactivation of C4b. The last
two points are essentially similar to those reported by Adams et
al.(9) and Oglesby et al.(40) , except
that the
In our
permanent expression system using CHO cells, N-glycosylation
diverged in
Some viruses and bacteria such as HIV (reviewed in Ref. 41),
Listeria (42), and Mycobacteria (43) activate the host
complement system to allow the deposition of C3b/C3bi on their own
membranes, and this deposited C3b/C3bi facilitates cellular invasion by
the microorganisms, even into their specific receptor-negative cells
via complement receptors. Naniche et al.(12) suggested
this possibility for MV, but no conclusive evidence supporting this
infective mechanism has been reported. The observation that the SCR1
domain is responsible for MV binding but not for the C3b/C4b
inactivation negates the involvement of C3b in MV-MCP interaction.
There are six mAbs that specifically recognize the SCR1 of MCP (). None of these mAbs, except for an mAb 4-23SB, however,
blocked MV infection in Vero cells and CHO transfectants. It may be
that the epitopes for these mAbs in SCR1 are not concerned in MV
infection. An mAb 4-23SB inhibited weakly MV infection in CHO
transfectants. The mAbs reported by Naniche et al.(44) indeed block MV infection but have not been
characterized with regard to the blocking of complement regulatory
activity. One mAb, GB24(45) , which recognizes the SCR3 or SCR4,
has been reported to block C3b and C4b binding to MCP (9) without
suppressing MV infection(13) . Although the binding sites of
C3b/C4b and MV in MCP map in nearby regions, no mAb reported to date
can completely blocked both MV binding and complement regulatory
activities of MCP. Hence, M177 and M75 (23) are the first mAbs
to simultaneously block both activities of MCP. Their epitopes were
mapped in the SCR2 domain, which is shared for both MV binding and
C3b/C4b inactivation. Evidence that mAbs 4-23SB and MH61 can block MV
infection in CHO transfectants but not in Vero cells may suggest
structural difference in the SCR domains of MCP between human and
monkey.
Besides MCP, CR2 and DAF have been reported to be receptors
for the Epstein-Barr virus (46, 47) and some strains of
the Echo virus(48) , respectively. The heads of these molecules
appear to be important for virus binding, similar to other virus
receptors(49) . There are many SCR proteins, which enhance cell
adhesion (reviewed in Refs. 50 and 51) mediated by integrin family
receptors and others(50) . Cell adhesion generally provides a
convenient environment for viral fusion/infection. It may be favorable
for microorganisms to adopt SCR proteins as a receptor, which
facilitate efficient infection by promoting cell-to-cell attachment.
However, further studies are required to substantiate this hypothesis.
The purified membrane form of MCP (10 ng) (3) was preincubated with
each mAb (10 µg). The mixtures were then incubated with
DACM-labeled C3b (10 µg) and factor I (0.5 µg) for 3 h at 37
°C in phosphate-buffered saline containing 0.02% Nonidet P-40, and
samples were resolved by SDS-PAGE (8% gels) under reducing conditions.
Cofactor activity was evaluated from the fluorescence intensity of the
We are grateful to Drs. H. Akedo, M. Matsumoto, and M.
Hatanaka (Center for Adult Diseases Osaka) for valuable discussions and
to Dr. B. Loveland for providing us with mAb E4.3.
Volume 270,
Number 25,
Issue of June 23, pp. 15148-15152, 1995
©1995 by The American Society for Biochemistry and Molecular Biology, Inc.
ABSTRACT
INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION FOOTNOTES
ACKNOWLEDGEMENTS
REFERENCES
()CD46 was first identified as a C3b-binding protein (1) distinct from other membrane complement-associated proteins
such as CR1 (CD35), CR2 (CD21), and decay-accelerating factor (DAF,
CD55) (reviewed in Ref. 2). MCP inactivates cell-bound C3b/C4b, acting
as a cofactor for plasma protease factor I(3, 4) , and
protects host cells from complement-mediated cell
damage(5, 6, 7) . This molecule composed of an
amino terminus of four short consensus repeating units (SCR), a Ser/Thr
(ST)-rich domain, 13 amino acids of unknown significance, a
transmembrane region, and a cytoplasmic tail (CYT)(8) . The
region responsible for complement regulation is the
SCR(9, 10) . The structural gene for MCP maps to
1q32(8) , where the genes of complement regulatory proteins,
C4b-binding protein, DAF, CR1, CR2, and factor H, are
clustered(11) . MCP is a member of the regulator of complement
activation gene family.
Cells, Antibodies, and Proteins
CHO cells were
obtained from American Type Culture Collection (ATCC). Vero cells,
green monkey erythrocytes, and MV, a modified Nagahata
strain(22) , were obtained from the Research Institute for
Microbial Diseases, Osaka University. Monoclonal antibodies (mAbs)
against MCP, M75, M160, and M177, were produced in our
laboratory(23) , E4.3 (24) was from Dr. B. Loveland
(Austin Institute, Melbourne, Australia), and other mAbs were reported
previously(25, 26) . Serum from a patient with subacute
sclerosing panencephalitis containing a high titer of anti-MV Ab was
obtained from Dr. M. B. A. Oldstone (The Scripps Research Institute, La
Jolla, CA)(27) .
cDNA Construction and Expression of SCR Deletion Mutants
of MCP in CHO Cells
MCP cDNA of ST
/CYT2 phenotype (8) was mutated using a T7-GEN In Vitro Mutagenesis Kit
(U. S. Biochemical Corp.). Briefly, oligonucleotides looping out the
sequences encoding a single SCR (corresponding to amino acids
1-61 of MCP, in reference to its amino acid sequence(8) )
were synthesized. For example, the oligonucleotide,
5`-TGGACATGTTTCTCTGGCATCGGAGAAGGA-3` was synthesized to delete SCR1
(
SCR1) of MCP. Similarly, oligonucleotide sequences were
determined to generate a mutant SCR2 (lacking the 62-124
amino acid sequence), SCR3 (lacking the 125-190 amino acid
sequence), and SCR4 (lacking the 192-251 amino acid
sequence). The nucleotide sequences of the resulting cDNAs were all
confirmed on a nucleotide sequencer (ABI 373A). Intact and mutated MCP
cDNAs were subcloned into the EcoRI/PstI-digested
expression vector pME18S(33) . The mutated cDNAs were again
confirmed on the nucleotide sequencer.
, 95% air at
37 °C. The cells were transferred to the same medium containing 0.7
mg/ml of hygromycin B (Sigma) for selection. The hygromycin-resistant
colonies were isolated with cloning cylinders and expanded in tissue
culture plates. The cDNAs incorporated into CHO cells were confirmed by
Southern blotting(35) . The expression of these mutants was
confirmed by flow cytometry using M160 (not shown), M177, and E4.3.
Flow Cytometry and Immunoblotting
The protein
levels expressed on the transfected cells (1 10
)
were assessed by flow cytometry (FACScan and/or Profile II) as
described previously (33) using M177 and E4.3, and fluorescein
isothiocyanate-labeled second Ab. CHO cells, transfected with vectors
only, pME18S and pSV2hph, were used as controls.
10
cells)
as reported previously(3) . The proteins were resolved by
SDS-PAGE (10-12.5% acrylamide), blotted onto membranes, and
detected with a mAb against MCP. The conditions for blotting analyses
were described in detail previously(10) .
Glycosidase Treatment
Solubilized SCR4 mutant
was mixed with 0.10 volume of 1% SDS and incubated with 1 unit of N-glycanase F. After incubation for 12 h at 37 °C, 1 unit
of N-glycanase F was further added and incubated for an
additional 12 h. Another SCR4 mutant was mixed with an equal
volume of incubation buffer (40 mM Tris maleate, 20 mMD-galactono--lactone, 2 mM calcium acetate,
0.2% Nonidet P-40, pH 6.0) and incubated with 100 microunits of
neuraminidase for 1 h at 37 °C. Then, 3 milliunits of O-glycanase and 1 unit of N-glycanase F were added
and incubated for 12 h. The sample was mixed with an additional 1 unit
of N-glycanase F and incubated for an additional 12 h at 37
°C. The glycanase-treated samples were resolved by SDS-PAGE and
Western blotted with M177 mAb, which recognizes SCR2.
Factor I-Cofactor Activity
A fluid-phase assay was
used (31, 32). Briefly, DACM-labeled C3b or C4b (10 µg) and factor
I (0.5 µg) were incubated for 3-12 h at 37 °C with
various amounts of MCP or its SCR deletion mutants, which were prepared
as follows. The samples solubilized from 2 10
cells
were prepared by acid precipitation(3) , and the amounts of
wild-type and mutant MCP were measured by sandwich enzyme-linked
immunosorbent assay(37) . SCR2 and SCR3 deletion mutants could
not be detected in this enzyme-linked immunosorbent assay, so the
concentrations of the mutants were estimated from the copy numbers of
the mutants on the CHO cells assuming the solubilization efficiencies
to be the same as that of the wild type. We obtained MCP samples of 7
µg/ml, and 1-10 µl was used as an MCP source. At timed
intervals, 10 µl of 10% SDS and 3 µl of 2-mercaptoethanol were
added to terminate the reaction and to reduce the substrates. The
samples were analyzed by SDS-PAGE (8-10% acrylamide), and the
percentage conversions of C3b to C3bi, and of C4b to C4d, were
determined by fluorescence spectrophotometry as described
previously(31, 32) . Cofactor activity was mostly
abrogated by the addition of M177(5) , suggesting that the
expressed MCP was a major cofactor in these CHO cells (not shown).
Complement-dependent Cytolysis of CHO
Transfectants
Anti-CHO cell Ab was used as a
sensitizer(33) , and the complement sources for the classical
and the alternative pathways were normal human serum diluted with
gelatin veronal buffer and normal human serum diluted with gelatin
veronal buffer containing 1 mM MgCl and 10 mM EGTA (Mg-EGTA), respectively. Briefly, the
transfected cells (2
10
/well) were seeded on
96-well plates. Fifteen h later, the cells were incubated with Cr (1 µCi/well) in complete medium for 3 h at 37
°C. After three washes with gelatin veronal buffer, the labeled
cells were incubated with anti-CHO Ab for 30 min at 4 °C, then 100
µl of 2-fold-diluted complement sources were added. The plates were
incubated for 60 min at 37 °C, and the released radioactivities
were measured in a
-counter. Cytotoxicity was calculated as
described previously (38). All determinations were performed in
triplicate.
MV Binding Assay
Cells to be assayed for MV
binding were detached from flasks at 80% confluence by the addition of
2 ml of phosphate-buffered saline containing 5 mM EDTA. After
two washes, aliquots containing 1 10
cells were
incubated for 2 h at 4 °C with 2 ml of concentrated MV (10 pfu/ml) in Dulbecco's modified Eagle's medium (DMEM)
containing 5% fetal calf serum. After three washes with DMEM, 5% fetal
calf serum, cells were incubated at 4 °C for 45 min with 5 µg
of anti-H mAb(27) . After three washes with 10 ml of DMEM, cells
were incubated with 5 µg of fluorescein isothiocyanate-labeled goat
anti-mouse IgG. The levels of the MV H protein in each CHO cell strain
were assessed by flow cytometry.
Determination of MV Infectivity
CHO cell clones
with or without a variety of MCP mutants were cultured at 70%
confluence in 24-well plates (Corning) for 15 h and infected with MV at
0.001-0.5 pfu/cell. Simultaneously, we performed plaque-forming
assays (27) and confirmed the correlation between CHO cell
syncytium formation and plaque formation. The syncytia formed were
counted, and the cytopathic characteristics of the CHO cell
transfectants (13) were observed 3 days post-infection.
Virtually, no background infection was observed at our doses of MV
within 3 days. Cells were photographed under a Nikon inverted
microscope (not shown).
Levels and Properties of SCR Deletion Mutants Expressed
on CHO Cells
The expression levels of the MCP mutants SCR1,
SCR2, SCR3, and SCR4 were examined by flow cytometry.
All SCR deletion mutants were translated into proteins and expressed on
the CHO cells (Fig. 1). The expression levels of MCP mutants were
similar on all clones used except for the SCR1 transfectant, the
density of which was elevated 3-4-fold. Based on the reaction
profile, the epitope of E4.3 was mapped in SCR1 (right panel of Fig. 1), consistent with the results of a previous
report(9) . Likewise, the epitope of M177 was mapped in SCR2 (left panel of Fig. 1). Epitope mapping was performed
with 10 mAbs against MCP, and the results are summarized in .
Figure 1:
Immunoblotting and flow cytometric
analyses for wild-type MCP and four MCP mutants. A, MCP
transfectants and control CHO cells were solubilized with Nonidet P-40,
and the insoluble materials were removed by centrifugation after acid
precipitation (see ``Materials and Methods''). The samples
were resolved by SDS-PAGE (10% acrylamide) (52) under nonreducing
conditions. Immunoblotting was performed with M177 or E4.3 (see also
Ref. 9) as primary Abs, and the membranes were subsequently stained
with alkaline phosphatase-conjugated goat anti-mouse IgG and color
reagents. The mean fluorescent shifts in flow cytometric analysis of
the cells are indicated under the figure. B, the SCR4
mutant was incubated with N- and/or O-glycanases,
resolved by SDS-PAGE, and Western-blotted using M177. Nontreated
SCR4 mutant (lane 1), SCR4 incubated with N- and O-glycanases (lane 2), and SCR4
mutant incubated with O-glycanase were resolved by SDS-PAGE
(12.5% acrylamide) and Western-blotted using
M177.
Immunoblotting suggested that the wild-type MCP has an
molecular mass of 57 kDa, consistent with that of the previously
reported ST/CYT2 form(6, 33) . The molecular
masses of SCR1, SCR2, and SCR3 mutants were 42, 44, and
54 kDa, respectively (Fig. 1A). The present results
supported those of previous reports that SCR1 and SCR2 are N-glycosylated (9, 39). The SCR4 mutant yielded two bands
on SDS-PAGE of 44 and 36 kDa, resulting from the single expected
nucleotide sequence. The two bands were accumulated into a single
33-kDa band on SDS-PAGE after N-glycanase treatment, and this
band was further decreased by 3 kDa by O-glycanase treatment (Fig. 1B). Thus, on CHO cells the SCR4 mutant
protein consists of two forms, one heavily glycosylated with a
molecular mass of 43 kDa and a lightly glycosylated 34-kDa form. All
mutants possessed O-linked sugars estimated on SDS-PAGE to be
3 kDa.
Complement Regulatory Function of the MCP
Mutants
Complement regulatory activities of the mutants were
determined by fluid-phase factor I-cofactor
assay(31, 32) . CHO(-) cells possessed minimal
C3b-C3bi converting activity (percent conversion by CHO(-) cells
was 20-22% under the conditions shown in ). With
DACM-labeled C3b as a substrate, SCR2-, SCR3-, and SCR4-deletion
mutants showed no cofactor activity relevant to the expressed MCP,
whereas SCR1 retained its activity (). Similar
results were obtained with another substrate, DACM-labeled C4b, except
that the cofactor activity for C4b cleavage remained minimal in the
SCR4 mutant (). M177 completely blocked this
SCR4-mediated C4b inactivation (data not shown), excluding the
possibility of involvement of other cofactors in the C4b cleavage.
Cr-labeled CHO cells with the mutants and the complement
sources for the classical and the alternative pathways ().
Two CHO cell clones expressing wild-type MCP were used as controls: one
clone, whose expression level of MCP was as high as that of
SCR1,
and the other clone, whose expression level of MCP was similar to those
of SCR2, SCR3, and SCR4. The SCR1 mutant expressed
as potent protective activity from complement attack as a wild-type.
Judging from the MCP copy numbers expressed on the CHO cells, SCR1
and wild-type MCP protected cells from the two pathways with similar
potencies. The SCR2 and SCR3 mutants showed no protective
activity from the two pathways, and the SCR4 had virtually no
effect on alternative pathway-mediated cell damage, while retaining
marginal protective activity against the classical pathway. Thus, the
degrees of cell protection in the mutants were essentially consistent
with their factor I-cofactor activities. The results are summarized in .
The Domain of MCP Responsible for MV Infection
MV
binding assay was performed by flow cytometry (). Binding
was observed in CHO cells expressing SCR3 and SCR4 mutants,
but not in those expressing SCR1 or SCR2. The degrees of MV
binding were in the order: wild type = SCR3
mutant>SCR4 mutant.
Replication of MV in MCP Mutant-expressing CHO
Cells
MV replicated in CHO transfectants expressing SCR3
and SCR4 mutants, as well as wild-type, whereas no replication
occurred in CHO transfectants expressing SCR1 or SCR2
mutants. The results were confirmed by determination of MV H protein
synthesis by immunostaining using subacute sclerosing panencephalitis
serum and mAb against MV H. The results again reinforce the notion that
the SCR1 and SCR2 domains are essential for MV infection and that MV
replication is permitted regardless of deletion of SCR3 or SCR4.
SCR4 mutant retained weak cofactor activity for factor
I-mediated C4b cleavage. They also determined the domains responsible
for C3b and C4b binding(9) . Our results taken together with
their findings indicate that the three ligands of MCP, C3b, C4b, and
MV, bind to different sets of SCR and confer distinct functions of MCP.
Hence, MCP is a multifunctional receptor with both classical and
alternative complement regulatory and MV binding activities.
SCR4 resulting in the two forms of the SCR4
protein. This is not the case in a transient COS cell expression system
reported by Adams et al.(9) , which may explain the
differences between previous results (9, 40) and our
present findings. That is, the presence of the two forms of the
SCR4 protein may explain the findings that our SCR4 mutant
retain, albeit weak, cofactor activity for C4b and that CHO cells
expressing SCR4 are less sensitive to MV than those expressing
SCR3 or wild-type MCP. It is not surprising that MCP molecules are
differently glycosylated in different cell lines. In fact, a variety of
MCP size variants secondary to cell type- and organ-specific
glycosylation have been reported(17, 18, 19) .
Table: Epitopes and effects on MCP functions of mAbs
chain and 1 fragment by spectrofluorometry (Hitachi F2000)
(31). Percent inhibition by each mAb was calculated assuming that the
percent conversion of the chain to the 1 fragment in the
absence of mAb was 100%. Monolayers of Vero or CHO cells in 24-well
plates were incubated at 37 °C for 60 min with each anti-MCP mAb
(25 µg/ml) in Ham's F-12, 10% fetal calf serum, then infected
with MV at a multiplicity of infection of 1 10
0.1 plaque-forming units (as determined on Vero cell
monolayers) per well for 2 h at 37 °C. The cells were washed three
times and cultured for 3 days. At timed intervals, the cytopathic
effect was evaluated under a Nikon inverted microscope.
Table: 0p4in
The assay was performed as in the classical
pathway, except that 40-fold-diluted anti-CHO Ab was used to potentiate
activation of the alternative pathway, and human serum was substituted
with Mg
-EGTA human serum. Values of CHO cell clones
expressing
3-fold more MCP or
SCR1 than other CHO cells
expressing SCR2, SCR3, and SCR4 are indicated in
parentheses.(119)
©1995 by The American Society for Biochemistry and Molecular Biology, Inc.
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A. M. Blom, B. O. Villoutreix, and B. Dahlback Mutations in {alpha}-Chain of C4BP That Selectively Affect Its Factor I Cofactor Function J. Biol. Chem., October 31, 2003; 278(44): 43437 - 43442. [Abstract] [Full Text] [PDF]
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Y. Mori, X. Yang, P. Akkapaiboon, T. Okuno, and K. Yamanishi Human Herpesvirus 6 Variant A Glycoprotein H-Glycoprotein L-Glycoprotein Q Complex Associates with Human CD46 J. Virol., April 15, 2003; 77(8): 4992 - 4999. [Abstract] [Full Text] [PDF]
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R. C. Riley, P. L. Tannenbaum, D. H. Abbott, and J. P. Atkinson Cutting Edge: Inhibiting Measles Virus Infection but Promoting Reproduction: An Explanation for Splicing and Tissue-Specific Expression of CD46 J. Immunol., November 15, 2002; 169(10): 5405 - 5409. [Abstract] [Full Text] [PDF]
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H. L. Greenstone, F. Santoro, P. Lusso, and E. A. Berger Human Herpesvirus 6 and Measles Virus Employ Distinct CD46 Domains for Receptor Function J. Biol. Chem., October 11, 2002; 277(42): 39112 - 39118. [Abstract] [Full Text] [PDF]
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Y. Mori, T. Seya, H. L. Huang, P. Akkapaiboon, P. Dhepakson, and K. Yamanishi Human Herpesvirus 6 Variant A but Not Variant B Induces Fusion from Without in a Variety of Human Cells through a Human Herpesvirus 6 Entry Receptor, CD46 J. Virol., June 5, 2002; 76(13): 6750 - 6761. [Abstract] [Full Text] [PDF]
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D. Christiansen, E. R. De Sousa, B. Loveland, P. Kyriakou, M. Lanteri, F. T. Wild, and D. Gerlier A CD46CD[55-46] chimeric receptor, eight short consensus repeats long, acts as an inhibitor of both CD46 (MCP)- and CD150 (SLAM)-mediated cell-cell fusion induced by CD46-using measles virus J. Gen. Virol., May 1, 2002; 83(5): 1147 - 1155. [Abstract] [Full Text] [PDF]
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A. Fukui, N. Inoue, M. Matsumoto, M. Nomura, K. Yamada, Y. Matsuda, K. Toyoshima, and T. Seya Molecular Cloning and Functional Characterization of Chicken Toll-like Receptors. A SINGLE CHICKEN TOLL COVERS MULTIPLE MOLECULAR PATTERNS J. Biol. Chem., December 7, 2001; 276(50): 47143 - 47149. [Abstract] [Full Text] [PDF]
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N. Ono, H. Tatsuo, K. Tanaka, H. Minagawa, and Y. Yanagi V Domain of Human SLAM (CDw150) Is Essential for Its Function as a Measles Virus Receptor J. Virol., February 15, 2001; 75(4): 1594 - 1600. [Abstract] [Full Text]
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N. Inoue, A. Fukui, M. Nomura, M. Matsumoto, K. Toyoshima, and T. Seya A Novel Chicken Membrane-Associated Complement Regulatory Protein: Molecular Cloning and Functional Characterization J. Immunol., January 1, 2001; 166(1): 424 - 431. [Abstract] [Full Text] [PDF]
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M. Kurita-Taniguchi, A. Fukui, K. Hazeki, A. Hirano, S. Tsuji, M. Matsumoto, M. Watanabe, S. Ueda, and T. Seya Functional Modulation of Human Macrophages Through CD46 (Measles Virus Receptor): Production of IL-12 p40 and Nitric Oxide in Association with Recruitment of Protein-Tyrosine Phosphatase SHP-1 to CD46 J. Immunol., November 1, 2000; 165(9): 5143 - 5152. [Abstract] [Full Text] [PDF]
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 J. Krushkal, O. Bat, and I. Gigli Evolutionary Relationships Among Proteins Encoded by the Regulator of Complement Activation Gene Cluster Mol. Biol. Evol., November 1, 2000; 17(11): 1718 - 1730. [Abstract] [Full Text] [PDF]
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D. Christiansen, P. Devaux, B. Réveil, A. Evlashev, B. Horvat, J. Lamy, C. Rabourdin-Combe, J. H. M. Cohen, and D. Gerlier Octamerization Enables Soluble CD46 Receptor To Neutralize Measles Virus In Vitro and In Vivo J. Virol., May 15, 2000; 74(10): 4672 - 4678. [Abstract] [Full Text]
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M. Manchester, D. S. Eto, A. Valsamakis, P. B. Liton, R. Fernandez-Muñoz, P. A. Rota, W. J. Bellini, D. N. Forthal, and M. B. A. Oldstone Clinical Isolates of Measles Virus Use CD46 as a Cellular Receptor J. Virol., May 1, 2000; 74(9): 3967 - 3974. [Abstract] [Full Text]
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D. Christiansen, B. Loveland, P. Kyriakou, M. Lanteri, C. Escoffier, and D. Gerlier Interaction of CD46 with measles virus: accessory role of CD46 short consensus repeat IV J. Gen. Virol., April 1, 2000; 81(4): 911 - 917. [Abstract] [Full Text]
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G. Wang, M. K. Liszewski, A. C. Chan, and J. P. Atkinson Membrane Cofactor Protein (MCP; CD46): Isoform-Specific Tyrosine Phosphorylation J. Immunol., February 15, 2000; 164(4): 1839 - 1846. [Abstract] [Full Text] [PDF]
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M. Teuchert, A. Maisner, and G. Herrler Importance of the Carboxyl-terminal FTSL Motif of Membrane Cofactor Protein for Basolateral Sorting and Endocytosis. POSITIVE AND NEGATIVE MODULATION BY SIGNALS INSIDE AND OUTSIDE THE CYTOPLASMIC TAIL J. Biol. Chem., July 9, 1999; 274(28): 19979 - 19984. [Abstract] [Full Text] [PDF]
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J. M. Lubinski, L. Wang, A. M. Soulika, R. Burger, R. A. Wetsel, H. Colten, G. H. Cohen, R. J. Eisenberg, J. D. Lambris, and H. M. Friedman Herpes Simplex Virus Type 1 Glycoprotein gC Mediates Immune Evasion In Vivo J. Virol., October 1, 1998; 72(10): 8257 - 8263. [Abstract] [Full Text] [PDF]
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M. K. Liszewski, M. K. Leung, and J. P. Atkinson Membrane Cofactor Protein: Importance of N- and O-Glycosylation for Complement Regulatory Function J. Immunol., October 1, 1998; 161(7): 3711 - 3718. [Abstract] [Full Text] [PDF]
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E. C. Hsu, F. Sarangi, C. Iorio, M. S. Sidhu, S. A. Udem, D. L. Dillehay, W. Xu, P. A. Rota, W. J. Bellini, and C. D. Richardson A Single Amino Acid Change in the Hemagglutinin Protein of Measles Virus Determines Its Ability To Bind CD46 and Reveals Another Receptor on Marmoset B Cells J. Virol., April 1, 1998; 72(4): 2905 - 2916. [Abstract] [Full Text] [PDF]
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Y. Doi, M. Kurita, M. Matsumoto, T. Kondo, T. Noda, S. Tsukita, S. Tsukita, and T. Seya Moesin Is Not a Receptor for Measles Virus Entry into Mouse Embryonic Stem Cells J. Virol., February 1, 1998; 72(2): 1586 - 1592. [Abstract] [Full Text] [PDF]
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C. J. Buchholz, D. Koller, P. Devaux, C. Mumenthaler, J. Schneider-Schaulies, W. Braun, D. Gerlier, and R. Cattaneo Mapping of the Primary Binding Site of Measles Virus to Its Receptor CD46 J. Biol. Chem., August 29, 1997; 272(35): 22072 - 22079. [Abstract] [Full Text] [PDF]
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M. K. Liszewski, M. Leung, W. Cui, V. B. Subramanian, J. Parkinson, P. N. Barlow, M. Manchester, and J. P. Atkinson Dissecting Sites Important for Complement Regulatory Activity in Membrane Cofactor Protein (MCP; CD46) J. Biol. Chem., November 22, 2000; 275(48): 37692 - 37701. [Abstract] [Full Text] [PDF]
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A. M. Blom, L. Kask, and B. Dahlback Structural Requirements for the Complement Regulatory Activities of C4BP J. Biol. Chem., July 13, 2001; 276(29): 27136 - 27144. [Abstract] [Full Text] [PDF]
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