Red blood cell calmodulin and Ca2+ pump ATPase: preliminary results of a species comparison

Membrane-bound ATPases of the red blood cells from five mammalian species were compared. Large differences were observed in the specific activities of (Mg2+)-ATPase, (Na++K+Mg2+)-ATPase and (Ca2+/Mg2+)-ATPase. by contrast, calmodulin activities of red blood cell lysates from the five species were similar. Results are considered in light of possible mechanisms for regulation of Na+ and Ca2+ in red blood cells.