Stimulation of mammalian and yeast phosphoprotein phosphatases by megamodulins from various sources

Phosphoprotein phosphatases (PPase) were isolated from either the rabbit cerebral cortex or Baker's yeast by excluding endogenous megamodulin with histone, and then by desalting cations with Bio-Gel P-6DG filtration. The stimulation of PPase in the presence of Mn2+ was greatly enhanced by megamodulins prepared from various sources including rabbit brain, Baker's yeast, wheat germ, and Escherichia coli (E. coli). Moreover, the augmented activity of PPase was also demonstrated in the presence of [megamodulin-Mn2+] complex.