{PDOC00340}
{PS00406; ACTINS_1}
{PS00432; ACTINS_2}
{PS01132; ACTINS_ACT_LIKE}
{BEGIN}
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* Actins signatures *
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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]-G-[DE]-E-A-Q-x-[RKQ](2)-G
-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-[IV]-[STA]-[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]-[LIVM]-T-E-[GAPQ]-x-[LIVMFYWHQ]-N-[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: November 1997 / 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.
     Curr. Opin. Cell Biol. 1:33-40(1990).
[ 4] Rubenstein P.A.
     BioEssays 12:309-315(1990).
[ 5] Meagher R.B., McLean B.G.
     Cell Motil. Cytoskeleton 16:164-166(1990).

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{END}
