Isolation and characterization of calmodulin from a murine macrophage-like cell line

Several lines of evidence implicate fluxes in the intracellular levels of CA++ and the cyclic nucleotiodes in the chemotactic, phagocytic, and cytotoxic responses of macrophages. Calmodulin, a ubiquitous small acidic Ca-binding protein, appears to link the intracellular second messengers--Ca++ and the cyclic nucleotides--through its ability to regulate numerous central metabolic enzymatic activities. A pure protein has been isolated and characterized from the macrophage-like cell line, P388D. This protein has been identified as calmodulin by demonstrating three of the Ca-dependent activities attributed to calmodulins. P388D calmodulin also has physiochemical properties similar to those of the previously characterized mammalian proteins. This study is the initial step of an examination of the role of this central regulatory protein in responses elicited by macrophages to external stimuli.