Girdin, a member of the CCDC88 (Hook related protein) family, is an actin binding protein involved with cell migration and maintaining cytoskeletal organization. Girdin has conserved domains at the N- and C-terminus that bind microtubules and actin, respectively. It enhances PI3-kinase dependent phosphorylation of proteins, most notably Akt. This same activity can contribute to tumor proliferation, invasion, and metastasis in breast, ovarian, prostate, and pancreatic tissues. Girdin is phosphorylated at three separate locations: Ser-1416, Ser-1674, and Tyr-1764. Ser-1416 is the primary Akt phosphorylation site, while Cyclin-dependent kinases interact with Girdin and phosphorylate Ser-1674. Multiple receptor tyrosine kinases can bind girdin and phosphorylate Tyr-1764.
