Interaction of calmodulin and other calcium-modulated proteins with mammalian and arthropod junctional membrane proteins.

Calmodulin and other calcium-modulated proteins bind in vitro to purified junctional polypeptides from rat liver gap junctions, bovine lens fiber junctions, a chymotryptic fragment from bovine lens junctions, and crayfish hepatopancreas gap junctions. The potential biological relevance of the interaction of calmodulin with junctional proteins is suggested by immunocytochemical localization of endogenous calmodulin in cortical regions of the cell where gap junctions exist. These observations provide a molecular basis for understanding the potential regulatory role of calmodulin on cell-cell communication channels in vivo. In addition, the calmodulin binding represents the first molecular homology that has been found for junctional channel proteins from mammalian and arthropod tissues.