Calexcitin: A signaling protein that binds calcium and GTP, inhibits potassium channels, and enhances membrane excitability

摘要

A previously uncharacterized 22-kDa Ca~2+- binding protein that also binds guanosine nucleotides was characterized, cloned, and analyzed by electrophysiological techniques. The cloned protein, calexcitin, contains two EF- hands and also has homology with GTP-binding proteins in the ADP ribosylation factor family. In addition to binding two molecules of Ca~2+, calexcitin bound GTP and possessed GTPase activity. Calexcitin is also a high affinity substrate for protein kinase C.