Centractin is an actin homologue associated with the centrosome

Actin is one of the most ubiquitous, abundant and well-conserved proteins of eukaryotes, participating in many crucial cellular processes including the maintenance of cell shape, motility and cell division. Actins from the most divergent sources still share amino-acid identities in excess of 70% (ref. 3). This may well explain why low-abundance homologues of actin have been difficult to isolate. Genes encoding distant relatives of actin in budding and fisson yeast have now been cloned. We report here the discovery of a vertebrate actin-like protein, which we name centractin. A full-length complementary DNA clone was isolated whose sequence reveals amino-acid identities with actin of over 50%, increasing to more than 70% when conservative amino-acid changes are considered. Northern analysis and western blotting indicate a ubiquitous tissue and species distribution. Morphological and biochemical criteria show that centractin is associated with centrosomes.