belongs to the gelsolin/villin group of actin binding proteins that are
typified by the possession of three or more gelsolin-like domains.
The tyoical villins have six of these (Matsudaira
et al, 1985; Arpin et al, 1988)
and in addition they have a so called "head piece" at the
C-terminus that is the largest single difference between gelsolin and
Click here for a
diagram of the domain structure of the Gelsolin/Villin family.
vertebrates, villin expression tends to limited to the brush
border. Surprisingly, perhaps villins or villin-like proteins are
expressed in protists and plants (Vidali
et al, 1999)and do not seem to be associated with
et al, 1998)
a protein from Dictyostelium has been isolated that despite
having gross domain structure similarity to vertebrate villin (Hofmann
et al, 1993) including the head
piece, appartently caps filaments but neither severs nor bundles
filaments (Hofmann et al, 1992).
Filament capping is regulated by polyphosphoinositide lipids but it is
far from clear as to why this protein needs to be so large and complex
since the same cell also produces a much smaller protein (cap 32/34)
that has similar properties. It was suggested that protovillin is
a villin precursor, possessing a rudimentary capping activity but has
not yet evolved the full severing, bundling activity. This view
assumes a rather predictive nature of molecular evolution and it seems
more probable that protovillin may be a degenerate villin that has lost
the properties that once it had. Even more likely is the
possibility that we have not yet fully understood the true function of
protovillin and this will provide a solution.
Another villin-like protein "supervillin"
has been isolated from neutrophils (Pestonjamasp
et al, 1997; Wulfkuhle
et al, 1999), a membrane and actin
binding protein with nuclear signal that drive it into the
Arpin, M., Pringault, E., Finidori,
J., Garcia, A., Jeltsch, J., Vandekerckhove, J. & Louvard, D. (1988)
Sequence of human villin: a large duplicated domain homologous with
other actin-severing proteins and a unique small carboxy-terminal domain
related to villin specificity., J. Cell Biol. 107, 1759-1766.
Hofmann, A., Noegel, A. A., Bomblies,
L., Lottspeich, F. & Schleicher, M. (1993) The 100 kDa F-actin
capping protein of Dictyostelium amoebae is a villin prototype ('protovillin'),
FEBS. 328, 71-76.
Marks, P. W., Arai, M.,
Bandura, J. L. & Kwiatkowski, D. J.
(1998) Advillin (p92): a new member of the gelsolin/villin family of
actin regulatory proteins, J.Cell Sci. 111, 2129-2136.
A gelsolin-like calcium-dependent actin-binding domain in villin., Nature.
Pestonjamasp, K. N., Pope, R. K.,
Wulfkuhle, J. D. & Luna, E. J.
(1997) Supervillin (p205): A novel membrane-associated, F-actin-binding
protein in the villin/gelsolin superfamily, J.Cell Biol. 139,
Wulfkuhle, J. D., Donina, I. E., Stark, N. H., Pope, R. K., Pestonjamasp,
K. N., Niswonger, M. L. & Luna, E. J. (1999) Domain analysis of
supervillin, an F-actin bundling plasma membrane protein with functional
nuclear localization signals., J.Cell Sci. 112, 2125-2136.