Modulation of ATPase activities in the central nervous system by the S-100 proteins.

The isomeric forms of bovine S-100a and S-100b have been shown to stimulate ATPase activities in fractions enriched in myelin and mitochondria isolated from the Gerbil brain and for S-100b more effectively than for calmodulin in erythrocytes or skeletal muscle. In the presence of Ca2+, S-100a produced a slight increase of ATPase activity in the mitochondrial fraction. However, S-100b in the presence of Zn2+ almost doubled the ATPase activity in brain myelin. S-100a, or S-100b, with or without Ca2+ and Zn2+ respectively, had no effect on the ATPase activity in mitochondria of the Gerbil liver. The observations may indicate a "second messenger" role for S-100b in the presence of Zn2+ in the Schwann cell.