Talin (Ser-425), Phosphospecific Antibody

Talin is an important cytoskeletal component of integrin adhesion sites. Calpins cleave talin precursor (240 kDa) into an amino-terminal globular head domain of 47 kDa and a carboxyl-terminal 190 kDa rod domain. The talin head domain contains a FERM domain that binds integrins, PIP kinase (Type I), and FAK. The rod domain has several vinculin-binding sites, a second integrin-binding site, and two actin-binding sites. These talin protein-protein interactions are critical for integrin activation, focal adhesion formation, and cell migration. Talin regulation may occur through phosphorylation and regulated degradation. The talin head domain binds Smurf1, an E3 ubiquitin ligase, and this interaction leads to talin head ubiquitylation and degradation. Cdk5 can phosphorylate Ser-425 in the head domain, and this inhibits both binding to Smurf1 and subsequent degradation. The S425A talin mutant resists Cdk5 phosphorylation, increases susceptibility to Smurf1-mediated ubiquitylation, and inhibits cell migration. Thus, talin head phosphorylation may be important for regulating adhesion stability and cell migration

The antibody detects a 240 kDa* protein corresponding to the molecular mass of Talin on SDS-PAGE immunoblots of human A431, rat PC12, and rabbit fibroblast cells treated with Calyculin A, but is not observed after lambda phosphatase treatment. This sequence is conserved in rat, mouse, and chicken Talin 1, as well as in Talin 2 (Ser-428) .