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{PDOC00340}
{PS00406; ACTINS_1}
{PS00432; ACTINS_2}
{PS01132; ACTINS_ACT_LIKE}
{BEGIN}
*********************
* Actins signatures *
*********************
Actins [1 to 4] are highly conserved contractile proteins that are present in
all eukaryotic cells. In vertebrates there are three groups of actin isoforms:
alpha, beta and gamma. The alpha actins are found in muscle tissues and are a
major constituent of the contractile apparatus. The beta and gamma actins co-
exists in most cell types as components of the cytoskeleton and as mediators
of internal cell motility. In plants [5] there are many isoforms which are
probably involved in a variety of functions such as cytoplasmic streaming,
cell shape determination, tip growth, graviperception, cell wall deposition,
etc.
Actin exists either in a monomeric form (G-actin) or in a polymerized form (F-
actin). Each actin monomer can bind a molecule of ATP; when polymerization
occurs, the ATP is hydrolyzed.
Actin is a protein of from 374 to 379 amino acid residues. The structure of
actin has been highly conserved in the course of evolution.
Recently some divergent actin-like proteins have been identified in several
species. These proteins are:
- Centractin (actin-RPV) from mammals, fungi (yeast ACT5, Neurospora crassa
ro-4) and Pneumocystis carinii (actin-II). Centractin seems to be a
component of a multi-subunit centrosomal complex involved in microtubule
based vesicle motility. This subfamily is also known as ARP1.
- ARP2 subfamily which includes chicken ACTL, yeast ACT2, Drosophila 14D,
C.elegans actC.
- ARP3 subfamily which includes actin 2 from mammals, Drosophila 66B, yeast
ACT4 and fission yeast act2.
- ARP4 subfamily which includes yeast ACT3 and Drosophila 13E.
We developed three signature patterns. The first two are specific to actins
and span positions 54 to 64 and 357 to 365. The last signature picks up both
actins and the actin-like proteins and corresponds to positions 106 to 118 in
actins.
-Consensus pattern: [FY]-[LIV]-[GV]-[DE]-E-[ARV]-[QLAH]-x(1,2)-[RKQ](2)-[GD]
-Sequences known to belong to this class detected by the pattern: ALL, except
for the actin-like proteins and 10 actins.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Consensus pattern: W-[IVC]-[STAK]-[RK]-x-[DE]-Y-[DNE]-[DE]
-Sequences known to belong to this class detected by the pattern: ALL, except
for the actin-like proteins and 9 actins.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Consensus pattern: [LM]-[LIVMA]-T-E-[GAPQ]-x-[LIVMFYWHQPK]-[NS]-[PSTAQ]-x(2)-
N-[KR]
-Sequences known to belong to this class detected by the pattern: ALL, except
for 5 actins.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: December 2004 / Patterns and text revised.
[ 1] Sheterline P., Clayton J., Sparrow J.C.
(In) Actins, 3rd Edition, Academic Press Ltd, London, (1996).
[ 2] Pollard T.D., Cooper J.A.
Annu. Rev. Biochem. 55:987-1036(1986).
[ 3] Pollard T.D.
"Actin."
Curr. Opin. Cell Biol. 2:33-40(1990).
PubMed=2183841
[ 4] Rubenstein P.A.
"The functional importance of multiple actin isoforms."
BioEssays 12:309-315(1990).
PubMed=2203335
[ 5] Meagher R.B., McLean B.G.
Cell Motil. Cytoskeleton 16:164-166(1990).
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{END}
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