Separation of extremely acidic proteins, S-100 proteins and calmodulin, in some bovine tissues and mammalian brains by two-dimensional electrophoresis in the absence of denaturing agents.

Extremely acidic proteins in bovine brain extracts, including S-100 proteins and calmodulin, were separated by two-dimensional electrophoresis in the absence of denaturing agents. The pattern was compared with the patterns of other bovine tissue extracts and also with those of brain extracts of other species. S-100 proteins (S-100 a and S-100 b) were specifically abundant in nerve tissues. A small amount of S-100 proteins was detected in heart extract. Extracts of liver and kidney did not have S-100 proteins, but each showed the distribution pattern of acidic proteins characteristic to the tissue. Calmodulin seemed to be present in all tissue extracts examined. Comparisons of the patterns of acidic proteins in brain extracts of various animal species suggest that S-100 proteins are more "variable" in structure than calmodulin.