|
|
|
|||||||
|
|||||||||
From the Departments of Biology and Pathology, Yale University,
New Haven, Connecticut 06520
INTRODUCTION Myosins are a large family of structurally
diverse mechanoenzymes that bind to F-actin and hydrolyze ATP to
produce mechanical force. Phylogenetic analysis of the myosin motor
domains has identified 11 distinct classes of myosin, seven of which
are expressed in vertebrates (for review see Ref. 1). These seven
myosin classes include conventional myosin, or myosin-II, and six more
recently identified unconventional myosin classes, myosins-I, -V, -VI,
-VII, -IX, and -X (see Fig. 1). At the N terminus, each
vertebrate unconventional myosin contains a conserved motor domain that
includes both the ATP binding and ATP-sensitive actin binding sites
(for review of the structure of the myosin motor domain see Ref. 2).
Following the motor is a light chain (LC)1
binding, regulatory ``neck'' domain comprised of 1-6 copies of a
24-30-amino acid repeat termed the IQ motif (3). For all vertebrate
unconventional myosins characterized to date, this neck domain serves
as a binding site for calmodulin (CaM), a member of the E-F hand
superfamily of calcium binding proteins. There is preliminary evidence
for additional non-CaM LC associated with myosin heavy chains (see
below). At the C terminus, each class has a distinct tail domain, which
provides sequences that can serve, for example, in dimerization or
membrane binding (Fig. 1). There is evidence for roles in protein
binding and/or enzymatic activities as well, and it is hypothesized
that each tail targets the myosin to its particular subcellular
location (for review see Ref. 1; Fig. 1).
Within a single cell or tissue, multiple myosins are present. For
example, in a porcine kidney proximal tubule cell line, expression of
myosins representing all seven classes has been observed (4). Indeed,
upward of 40 different full-length or partial cDNAs have been
identified in vertebrates which, by comparison at the amino acid level,
can be grouped as 14 distinct unconventional myosins (Table
I). As recently confirmed by mapping studies,
vertebrates express at least six myosins-I, two myosins-V, one
myosin-VI, two myosins-VII, two myosins-IX, and one myosin-X in
addition to 10 different isoforms of myosin-II (Table I)
(1).2 We will be summarizing the most
recent advances in the study of vertebrate unconventional myosins
focusing on the two major approaches taken to better understand the
functions of unconventional myosins: traditional biochemical and cell
biological approaches and genetic studies.
Identified vertebrate unconventional myosin
cDNAs
Myosin-I All vertebrate myosins-I consist of a 110-130-kDa heavy chain and
1-6 CaM LC (Fig. 1). A comparison of the primary structure of the head
domains of known myosins-I indicate that there are at least 4 distinct
subclasses (6, 7) (reviewed in Ref. 1), all of which are expressed in
vertebrates. The working hypothesis is that each subfamily performs
distinct sets of functions; however, there are no genetic studies that
firmly establish a function for a vertebrate myosin-I.
It has been more than two decades since the
initial purification of myosins-I of this subclass from
Acanthamoeba (8), and the wealth of information with regard
to the biochemical properties, functional domain structure, and
subcellular localization of the multiple myosins-I expressed in
Acanthamoeba has been reviewed in detail elsewhere (for
references see Refs. 1, 9, and 10). Several subclass I myosins have
been identified in vertebrates (see Table I). Based on primary
structure, as well as functional domain mapping studies of
Acanthamoeba myosins-I, the tails of these myosins have been
divided into three tail homology (TH1-3) subdomains. The TH-1 domain,
positioned immediately after the neck domain is rich in basic residues
and may effect binding to acidic phospholipids. A similar basic domain
comprises the full tail of the other three known myosin-I subclasses.
The TH-2 domain is rich in proline and also either glycine, as in human
myosin-IC (Fig. 1), or glycine/alanine and glycine/glutamate, as in
Dictyostelium myosins-I. For Acanthamoeba
myosins-I, it has been shown that this domain exhibits ATP-insensitive
actin binding, thus allowing this myosin to cross-link actin filaments.
This critical feature has not been established for vertebrate subclass
I myosins. The TH-3 domain consists of a Src homology-3 (SH3) domain.
In Acanthamoeba, it has been shown that the head domain of
this class of myosin-I must be phosphorylated to be active by a
specific myosin-I heavy chain kinase at a serine or threonine residue
in a conserved portion of the motor domain (reviewed in Ref. 10). None
of the known vertebrate myosins-I contain either a serine or threonine
at this site (the TEDS site (11)).
The expression profile of human myosin-IC (12) and its rat ortholog,
Myr3 (13), indicate that this myosin-I is present in a wide range of
tissues and cell types. Localization studies have been restricted thus
far to cultured normal rat kidney cells, and in these cells, Myr3
exhibits a punctate distribution in the cytoplasm and is concentrated
in F-actin-rich, elongate structures at sites of cell-cell contact that
are distinct from adhesion plaques (13). Interestingly, Concanavalin A
treatment of these cells increases the number of these Myr3-rich
structures at sites of cell contact. Although no subclass I myosin-I
has been purified from a vertebrate source, analysis of the
ATP-dependent actin binding of Myr3 present in tissue
extracts suggests that the TH-3 domain of Myr3 may modulate the
interaction of this myosin-I with actin.
The founding
member of this myosin-I subclass is chicken brush border (BB) myosin-I
(Fig. 1, Table I). BB myosin-I is expressed in the intestinal epithelia
of the large and small intestine, where it comprises the spirally
configured bridges that tether the microvillar actin core to the plasma
membrane (reviewed in Ref. 14). In contrast, to BB myosin-I, the other
members of this subclass, myosin-I Since BB myosin-I is among the best characterized vertebrate
unconventional myosins, it serves as an excellent test case to
determine if in vitro expression systems can be used for
detailed structural and functional analysis of these myosins. Thus, it
is noteworthy that expressed chicken BB myosin-I, with properties
comparable with tissue-purified protein, has been obtained from
transfected COS cells (18) and most recently using the baculovirus
expression system in Sf9 cells (19).
A fundamental question to address for these and all other
unconventional myosins is what role the tail domain plays in
subcellular localization. In the case of BB myosin-I, Footer and
Bretscher (20) observed targeting of BB myosin-I to dorsal microvilli
of fibroblasts (i.e. not an enterocyte) injected with this
myosin. This surprising result suggests that the head domain, through
its interaction with the microvillar core bundle, may drive assembly of
BB myosin-I rather than its interaction with a specific docking protein
complex in the microvillar membrane.
The importance of the head domain in subcellular localization has also
been addressed for Myr1, as well as the subclass 3 myosin-I, Myr2.
Rüppert et al. (21) compared the localization of
full-length versus tail domains of Myr1 and -2 in normal rat
kidney cells transfected with appropriate epitope-tagged constructs. In
these cells, the endogenous Myr1 associates with the plasma membrane,
including membrane ruffles, while Myr2 exhibits a punctate pattern
throughout the cytoplasm (21). In transfected cells, the full-length,
epitope-tagged protein co-localized with the endogenous myosins.
Overexpressed epitope-tagged myosin tail domains did not affect the
location of the native protein and exhibited much higher levels of
cytosolic expression suggesting that the head domain is necessary for
proper subcellular targeting.
Lewis and Bridgman (22) have analyzed the location of myosin-I Myosin-I The most significant finding with respect to determining a function for
myosin-I The only vertebrate member of
this subclass to be fully cloned thus far is rat Myr4 (Table I),
although homologs of this subclass have been identified in both
Drosophila and Caenorhabditis elegans (1, 29).
Like other vertebrate myosins-I the light chains of Myr4 are CaM (7),
although the two IQ motifs that comprise the neck domain exhibit
differing Ca2+ sensitivities for CaM binding, based on
studies using bacterially expressed protein (7). These studies also
revealed a non-IQ, Ca2+ requiring a calmodulin binding site
within the tail domain.
Myosin-V Myosins-V, unlike myosins-I, are two-headed as they self-associate
via an Genetically, myosins-V have been implicated in membrane movements. Mice
with mutations in myosin-V exhibit a lightened coat coloring or
dilute phenotype. This is due to a defect in transport of
the melanosomes, or pigment granules, to the dendrites of melanocytes,
which results in inefficient phagocytosis of the pigment by the
keratinocytes of the hair shaft (summarized in Ref. 31). To date,
actin-based movement of melanosomes has not been observed, but
supporting a role for myosin-V in melanosome movements, preliminary
work (32) has shown that myosin-V can be immunoprecipitated from
isolated melanosomes from normal animals but not from dilute
mice.
Other alleles of dilute, termed dilute-lethal, in
addition to the lightened coat coloring also produce an abnormal
postnatal neurological disorder characterized by convulsions and death
by 3 weeks of age (31). No obvious defect in neuroanatomy of these mice
has been observed, and the basis for the neurological abnormalities is
not understood. Because of the abundant expression of myosin-V within
neurons, but not within other cells of the nervous system, it has been
postulated that, by analogy to the melanocyte, myosin-V is also
necessary for organelle movement in neurons.
Recent work indicates that, indeed, there is a potent actin-based
motility, which occurs within vertebrate neurons as well. Using
video-enhanced DIC microscopy, Evans and Bridgman (33) observed
movement of particles within the growth cones of neurons cultured in
low doses of nocodazole and cytochalasin, inhibitors of microtubule and
microfilament assembly, respectively. This treatment allowed for
visualization of movements of particles along actin bundles at rates of
0.48 µm/s, a rate very similar to what is seen in vitro
for chick brain myosin-V. In preliminary work, Evans and colleagues
(34) have located myosin-V by immunoelectron microscopy within these
growth cones and have found it in association with small (50-100 nm)
organelles, actin, and plasma membrane domains. These results strongly
suggest that myosin-V is indeed an organelle motor in brain.
Recent biochemical studies on purified chick brain myosin-V indicate
that the ATP-dependent actin binding and ATPase properties
of this motor are consistent with that of an organelle motor (35). In
striking contrast to conventional myosins and BB myosin-I, the steady
state Mg-ATPase of myosin-V is maximally activated at very low F-actin
concentrations, with a KATPase of ~1
µM actin. It will be critical to determine if these
steady state measurements indicate that myosin-V can remain associated
with an actin filament for longer periods than conventional myosin
during its duty cycle, a critical feature for a motor expected to
translocate organelles.
Myosin-VI Compared with myosins-I and -V much less is known of the
biochemistry of myosin-VI. Sequence analysis of myosin-VI revealed that
the 145-kDa heavy chain has a 200-aa coiled-coil domain in its tail,
which could allow for dimerization (Fig. 1). In agreement with the
presence of a single IQ motif in the neck domain, coimmunoprecipitation
studies showed that myosin-VI was associated with CaM (36). The neck
domain of myosin-VI is unusual, however, as there is a 50-aa linker
between the end of the motor domain and IQ motif (Fig. 1). It is
unknown if this linker domain serves as a binding site for a novel LC.
The tail domain of myosin-VI is unique, and it is remarkably conserved
among myosin-VI homologs (36). Using extracts from rat kidney,
myosin-VI was shown to bind F-actin in an ATP-sensitive fashion (36).
Myosin-VI motility has not been observed yet, however, perhaps due to
regulation by phosphorylation of the heavy chain at a conserved
threonine residue (TEDS site) similar to what is seen for
Acanthamoeba myosins-I (11, 36).
Myosin-VI is ubiquitously expressed, but recent genetic studies suggest
that its most critical function is in the maintenance of the cells of
the inner ear. Avraham and colleagues (37) were interested in
identifying the mouse recessive deafness gene, Snell's
waltzer (sv). sv mice are profoundly deaf
due to a complete degeneration of the neuroepithelium of the cochlea
and exhibit head tossing and circling phenotypes characteristic of
vestibular dysfuncion. Positional cloning of sv identified
it as the gene for mouse myosin-VI, encoding a polypeptide 91%
identical at the amino acid level to porcine myosin-VI (37). Myosin-VI
protein was located within the neuroepithelium of the cochlea and was
found to be expressed by the inner and outer hair cells of the organ of
Corti (37). Within these cells it was seen to be enriched at the
cuticular plate, an actin-rich structure at the bases of the
stereocilia (37). This location is reminiscent of previous
immunolocation studies, which showed that myosin-VI was enriched within
the subapical terminal web region of brush border containing polarized
epithelial cells (36, 38). These locations have suggested a role for
myosin-VI is membrane movements, endocytosis, or membrane recycling
events within polarized cells.
Myosin-VII Myosin-VIIa was recently identified as the gene defective in
mouse shaker-1, a recessive deafness mutant (39) and in
human Usher syndrome type 1B, a recessive disease characterized by
congenital deafness, vestibular dysfunction, and retinitis pigmentosa
(40). Since these genetic studies, the complete cDNA of human
myosin-VIIa has been characterized.3 As
diagrammed in Fig. 1, myosin-VIIa has an N-terminal motor, five IQ
motifs in its neck domain, and a short coiled-coil domain at the
proximal portion of the tail. The remainder of the tail is comprised of
two large ~460-amino acid repeats. Each repeat contains two domains,
which have been called the MyTH4 domain and the talin-homology
domain.3 The MyTH4 domain, for Immunolocation studies have focused on the expression of myosin-VIIa
within tissues affected in Usher syndrome. In the cochlea, myosin-VIIa
was expressed exclusively by the sensory hair cells of the organ of
Corti. Within the inner and outer hair cells, myosin-VIIa expressed
within the stereocilia, as well as within the cuticular plate and
throughout the cell body (43). This is distinct from the location of
myosin-VI, which was not located to the stereocilia, and from
myosin-I In the rat retina, myosin-VIIa was expressed exclusively by the
pigmented epithelial cells (43). This result suggests that the
retinitis pigmentosa observed in Usher patients is due to a defect in
this cell layer. This is quite unique, as all previously identified
retinitis pigmentosa genes are defects within the phototransduction
machinery (44). Within the retinal pigmented epithelial (RPE) cells,
myosin-VIIa was enriched at the apical plasma membrane (43). On the
apical surface of RPE cells are villi, actin-rich structures involved
in phagocytosis of spent photoreceptor outer segments. This
phagocytosis is essential for photoreceptor viability, as defects in
this process have been shown to lead to retinal degeneration in the RCS
rat (45). In these animals, cellular debris accumulates in the
intercellular space between the outer segments and the RPE layer,
leading to photoreceptor cell death. Perhaps myosin-VIIa serves an
essential role in this phagocytic process.
Myosins-IX and -X, Links to Cell Signaling Pathways Myosins-IX motors are unusual in that they have an N-terminal
extension, which is distinct from all other myosins as well as an
insert of 150 aa in the actin binding loop (reviewed in Ref. 1),
suggesting that the class IX myosins may have unusual mechanochemical
properties. Also of interest is a striking tail domain, which contains
a chimerin-like apposition of a zinc-binding motif and a
GTPase-activating protein (GAP) domain (Fig. 1). This sequence homology
suggests that myosins-IX may serve as GAP proteins for the Rho/Rac
family of Ras-like GTP-binding proteins. As reviewed recently (46),
assays performed using bacterially expressed fusion proteins containing
domains from Myr5, a rat myosin-IX, have shown that the tail does
indeed bind zinc, but, unlike chimerin, the Myr5 GAP domain
preferentially activated the GTPase activity of Rho, and only
marginally activated Rac1 (47). Rac and Rho have both been shown to be
critical in the membrane reorganizations involved in the induction of
membrane ruffling and the assembly of focal adhesions in fibroblasts.
Myosins-IX may therefore form a direct link between the actin
cytoskeleton and Rho-dependent signaling pathway (reviewed
in Ref. 48).
Recently a human class IX cDNA was identified, myosin-IXb (49).
Myosin-IXb is highly homologous to Myr5, except at the C-terminal
100-aa tip of the tail suggesting that myosins-IX are alternatively
spliced. Expression of myosin-IXb was characterized in a myelocytic
cell line HL-60, where it was shown that myosin-IXb exhibited an
increase in expression level and a redistribution in location upon
differentiation of these cells from promyelocytic to macrophage states
(49). This suggests a role for myosin-IXB in the G-protein-coupled
actin-based changes in cell shape observed upon differentiation in
myelocytic lineages.
Another unconventional myosin with a likely association with G-protein
pathways is myosin-X, the most recently identified vertebrate myosin
class. First identified in frog (50), myosin-X has now been completely
cloned from cow4 and is shown schematically in
Fig. 1. The tail of myosin-X contains a short portion of coiled-coil as
well as three pleckstrin homology (PH) domains. PH domains have been
found in a large number of proteins that interact with both the
membrane cytoskeleton and signal transduction machinery (reviewed in
Ref. 51). PH domains have been shown to bind to heterotrimeric GTP
binding proteins as well as to phosphatidylinositol 1,4,5-bisphosphate
(41), so, like myosins-IX, myosin-X has the potential to play a role
linking the signal transduction pathway to the actin
cytoskeleton.
Conclusions Clearly, actin-based motilities are critical for the proper
function and development of such diverse cell types as sensory hair
cells, melanocytes, retinal epithelia, and neurons. In addition to
their presumed functions in motile processes, the studies described
here highlight the potential roles of unconventional myosins in signal
transduction and in direct mechanochemical regulation of membrane
channels.
FOOTNOTES Acknowledgments We thank D. P. Corey and R. E. Cheney for sharing unpublished data on myosin-X.
REFERENCES
Volume 271, Number 28,
Issue of July 12, 1996
pp. 16431-16434
©1996 by The American Society for Biochemistry and Molecular Biology, Inc.
MINIREVIEW:
INTRODUCTION
Myosin-I
Myosin-V
Myosin-VI
Myosin-VII
Myosins-IX and -X, Links to Cell Signaling Pathways
Conclusions
FOOTNOTES
Acknowledgments
REFERENCES
Fig. 1.
Vertebrate myosins. Schematic showing
the motor (red), neck, and tail domains of vertebrate
myosins. IQ repeats are shown as black rectangles in the
neck domain. Insertions within the motor domains of some myosin classes
are shown in magenta. See text for details on the various
myosin tail domains. Two examples of myosin-I are shown, specifically a
subclass 1 (myosin-IC) and a subclass 2 (brush border myosin-I).
Subclasses 3 and 4 have a structure similar to brush border myosin-I,
although they vary in the number of IQ motifs within the neck
domain.
*
indicates partial cDNA clone. For references see (Ref. 1),
except for rat brush border myosin-I (5) and rat myosin-I 
(22), both
of which were recently cloned.
and Myr1 (Table I), have been
shown to be expressed in a wide range of tissues. Both BB myosin-I and
myosin-I/Myr1 contain multiple neck-associated CaM LC. Myr1 has been
purified from liver (15) and, like BB myosin-I (for review of
biochemical studies of BB myosin-I see Refs. 14, 16, and 17), Myr1
exhibits a relatively slow (30-50 nm/s) in vitro motility
that is inhibited by calcium.
within cultured rat superior cervical ganglion cells at the light and
electron microscopic level of resolution. Myosin-I was observed to
have a punctate distribution within the superior cervical ganglion with
an enrichment at the cell cortex. Interestingly, these punctae were
found to not be membranous organelles but rather reflected an
association with regions of plasma membrane adjacent to the actin-rich
cortex (22). These results force us to rethink the assumption that a
punctate staining implicates an association with vesicles.
/Myr2
was first purified
from bovine brain and adrenal gland, and the initial biochemical
studies indicating that it contains multiple CaM LM and exhibits
enzymatic properties similar to that of BB myosin-I have been reviewed
elsewhere (1, 17). cDNAs encoding presumed orthologous heavy chains
have been cloned from frog and rat (termed Myr2; Table I) and, like
members of subclass 2, myosin-I is expressed in a wide range of
tissues. Localization studies using different antibodies to this
myosin-I have given conflicting results even in the same cell type.
Myosin-I has been reported to be associated with the cell periphery,
including membrane ruffles (23), as well as with the cytokinetic furrow
(24). This is in contrast to Ruppert et al. (21) who
reported that this myosin was associated with discrete puncta
throughout the cytoplasm. As noted by these authors, this discrepancy
may well be the result of cross-reactivity of the original myosin-I
antibodies with other myosins-I (such as myosin-I).
has been the demonstration that this myosin (or related
immunogen) is expressed in the hair cells of the frog sacculus, where
it is restricted in location to the tips of the hair bundles (25). As
recently reviewed (26), myosin-I has been proposed, based on this
localization, to be the actin-based adaptation motor, which gates the
tip link-associated cation channels that open in response to mechanical
stimulation of the hair cell bundles. As discussed in detail elsewhere
(26, 27), a critical property of the myosin serving as the adaptation
motor is that, upon influx of Ca2+ due to the mechanical
opening of the transduction channel, the mechanochemical activity of
the motor should be inhibited. Consistent with this model are the
recent studies of Zhu et al. (28), who have conducted an
extensive analysis of bovine myosin-I made in Sf9 cells using the
baculovirus expression system. In contrast to the initial enzymatic
studies using tissue-purified protein, these authors found that
expressed myosin-I is a much faster motor, with rates that are
comparable with some conventional myosins and myosin-V (500 nm/s
versus 60 nm/s for BB myosin-I). Most importantly, the
in vitro motility of this myosin is inhibited by
Ca2+ even in the presence of saturating CaM, a property
consistent with its potential role as the tip link motor.
-helical coiled-coil portion of the tail (Fig. 1). All
myosins-V contain six IQ motifs and have been shown to be associated
with multiple CaM LCs. Purified myosin-V is also associated with two as
yet unidentified LC distinct from calmodulin. The tail domain of
myosin-V is of unknown function but may serve to target this myosin to
organelles. Interestingly, sequences similar to the tail of myosin-V
were recently uncovered in the non-myosin proteins human AF-6 and its
homolog Drosophila Canoe (30), suggesting that the tail of
myosin-V contains a conserved functional domain as is seen for
many of the other unconventional myosin classes (Fig. 1).
osin
ail omology 4, is shared by myosin-VIIa and
Acanthamoeba high molecular weight myosin-IV and is of
unknown function. The talin-homology domain, however, is a conserved
sequence shared by members of the band 4.1 superfamily and has been
shown for both talin and band 4.1 to bind to acidic phospholipids
(reviewed in Ref. 42). These sequence homologies suggest that the tail
of myosin-VIIa targets the motor to the plasma membrane, as is seen for
ezrin, moesin, and other band 4.1 members.
, the putative adaptation motor, which was specifically
located to the stereocilia tips. Since myosin-VIIa is expressed along
the entire length of the stereocilia and is potentially a membrane
binding protein, myosin-VIIa may serve a structural role, as is seen
for brush border myosin-I, tethering the polarized actin filaments of
the stereocilia to the plasma membrane.
1
The abbreviations used are: LC, light chain;
CaM, calmodulin; TH, tail homology; BB, brush border; aa, amino acid;
RPE, retinal pigmented epithelial; GAP, GTPase-activating protein; PH,
pleckstrin homology.
2
Hasson, T., Skowron, J. F., Gilbert, D. J.,
Avraham, K. B., Perry, W. L., Bement, W. M., Anderson, B. L., Sherr, E. H., Greene, L. A., Ward, D. C., Corey, D. P., Mooseker, M. S.,
Copeland, N. G., and Jenkins, N. A. (1996) Genomics, in
press.
3
Chen, Z.-Y., Hasson,T., Kelley, P. M.,
Schwender, B. J., Schwartz, M. F., Remakrishnan, M., Kimberling, W. J.,
Mooseker, M. S., and Corey, D. P. (1996) Genomics, in
press.
4
D. P. Corey and R. E. Cheney, unpublished
results.
©1996 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:
|
|
 |
|
  N. Umeki, H. S. Jung, S. Watanabe, T. Sakai, X.-d. Li, R. Ikebe, R. Craig, and M. Ikebe The tail binds to the head-neck domain, inhibiting ATPase activity of myosin VIIA PNAS, May 26, 2009; 106(21): 8483 - 8488. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. W. Provance Jr., C. R. Gourley, C. M. Silan, L. C. Cameron, K. M. Shokat, J. R. Goldenring, K. Shah, P. G. Gillespie, and J. A. Mercer From the Cover: Chemical-genetic inhibition of a sensitized mutant myosin Vb demonstrates a role in peripheral-pericentriolar membrane traffic PNAS, February 17, 2004; 101(7): 1868 - 1873. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Mori, T. Furusawa, T. Okubo, T. Inoue, S. Ikawa, N. Yanai, K. J. Mori, and M. Obinata Genome Structure and Differential Expression of Two Isoforms of a Novel PDZ-Containing Myosin (MysPDZ) (Myo18A) J. Biochem., April 1, 2003; 133(4): 405 - 413. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Zhu, K. Beckingham, and M. Ikebe High Affinity Ca2+ Binding Sites of Calmodulin Are Critical for the Regulation of Myosin Ibeta Motor Function J. Biol. Chem., August 7, 1998; 273(32): 20481 - 20486. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J.-D. Huang, V. Mermall, M. C. Strobel, L. B. Russell, M. S. Mooseker, N. G. Copeland, and N. A. Jenkins Molecular Genetic Dissection of Mouse Unconventional Myosin-VA: Tail Region Mutations Genetics, April 1, 1998; 148(4): 1963 - 1972. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Wu, V. Lytvyn, D. Y. Thomas, and E. Leberer The Phosphorylation Site for Ste20p-like Protein Kinases Is Essential for the Function of Myosin-I in Yeast J. Biol. Chem., December 5, 1997; 272(49): 30623 - 30626. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. L. Joyal, D. J. Burks, S. Pons, W. F. Matter, C. J. Vlahos, M. F. White, and D. B. Sacks Calmodulin Activates Phosphatidylinositol 3-Kinase J. Biol. Chem., November 7, 1997; 272(45): 28183 - 28186. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. A. Louis, J. D. Pino, K. L. Schmeichel, P. Pomies, and M. C. Beckerle Comparison of Three Members of the Cysteine-rich Protein Family Reveals Functional Conservation and Divergent Patterns of Gene Expression J. Biol. Chem., October 24, 1997; 272(43): 27484 - 27491. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Nowak, L. Pestic-Dragovich, P. Hozak, A. Philimonenko, C. Simerly, G. Schatten, and P. de Lanerolle Evidence for the Presence of Myosin I in the Nucleus J. Biol. Chem., July 4, 1997; 272(27): 17176 - 17181. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Xu, K. I. Mitchelhill, B. Kobe, B. E. Kemp, and H. G. Zot The myosin-I-binding protein Acan125 binds the SH3 domain and belongs to the superfamily of leucine-rich repeat proteins PNAS, April 15, 1997; 94(8): 3685 - 3690. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Brzeska and E. D. Korn Regulation of Class I and Class II Myosins by Heavy Chain Phosphorylation J. Biol. Chem., July 19, 1996; 271(29): 16983 - 16986. [Full Text] [PDF]
|
|
|
|
 |
|
 P.G. Gillespie, T. Hasson, J.A. Garcia, and D.P. Corey Multiple Myosin Isozymes and Hair-cell Function Cold Spring Harb Symp Quant Biol, January 1, 1996; 61(0): 309 - 318. [Abstract] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| All ASBMB Journals | Molecular and Cellular Proteomics |
| Journal of Lipid Research | ASBMB Today |