BD Transduction Laboratories™ Purified Mouse Anti-Espin

Actin-binding proteins regulate the polymerization and depolymerization of actin, connect actin-based structures to membranes and to other cytoskeletal elements, power the movement of actin filaments, and cross-link actin filaments into bundles. Espins are actin binding and bundling proteins. The two isoforms of espin are the 30 kDa small espin found in brush border cells and the 110 kDa espin found in testis. Espin contains eight ankyrin repeats in the N-terminal region, two proline-rich peptides, an ATP/GTP binding P-loop domain, and a C-terminal actin bundling domain. Small espin is composed of the C-terminal actin bundling domain and a unique region at the N-terminus. Espin binds to actin with a higher affinity than small espin and is more efficient at actin bundling. During spermiogenesis, espin accumulates, along with forming parallel actin bundles, at the ectoplasmic specialization. These actin bundles anchor and position the spermatid within the seminiferous epithelium. Other actin binding proteins, such as α-actinin, vinculin, and fimbrin, have also been implicated in the formation of ectoplasmic specialization, however espin appears to function specifically in the testes.