Calcium binding protein from porcine intestine binds to phosphatidylserine vesicles in the presence of calcium.

Protein II, a 32K cytoskeleton-associated protein isolated from porcine intestinal epithelium, binds to vesicles composed of phosphatidylserine in the presence, but not the absence, of 10 microM Ca2+. Binding was saturable and was specifically inhibited by chelation of free Ca2+ with EGTA. Binding was also inhibited by trifluophenothiazine. Vesicles composed of dimyristoylphosphatidylcholine did not bind protein II, suggesting that interaction with phosphatidylserine was selective. These properties are consistent with a possible role for protein II in Ca-regulated cytoskeleton-cell membrane events.