|PROSITE documentation PDOC00340 [for PROSITE entry PS01132]|
Actins [1,2,3,4] are highly conserved contractile proteins that are present in all eukaryotic cells. In vertebrates there are three groups of actin isoforms: α, β and γ. The α actins are found in muscle tissues and are a major constituent of the contractile apparatus. The β and γ actins co-exists in most cell types as components of the cytoskeleton and as mediators of internal cell motility. In plants  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:
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.Last update:
December 2004 / Patterns and text revised.
PROSITE methods (with tools and information) covered by this documentation:
|1||Authors||Sheterline P., Clayton J., Sparrow J.C.|
|Source||(In) Actins, 3rd Edition, Academic Press Ltd, London, (1996).|
|2||Authors||Pollard T.D., Cooper J.A.|
|Source||Annu. Rev. Biochem. 55:987-1036(1986).|
|Source||Curr. Opin. Cell Biol. 2:33-40(1990).|
|Title||The functional importance of multiple actin isoforms.|
|5||Authors||Meagher R.B., McLean B.G.|
|Source||Cell Motil. Cytoskeleton 16:164-166(1990).|