Measurement of the potential activity of the type-1 and type-2 protein phosphatases in the crude tissue extract

Abstract

Although activation and conversion of the inactive/latent high-molecular-weight phosphatases to the Mr = ∼ 35,000 catalytic subunits can be achieved by several procedures including freezing/thawing in 0.2 M 2-mercaptoethanol and digestion by proteolytic enzymes, strong indications have been obtained that they are distinct stimulating processes. For instance, when pig brain extracts were treated with trypsin, the type-1 phosphatase could be stimulated ∼40 fold while the type-2 phosphatase was not slightly modified. Conversely, when the same crude extracts were treated with freezing/thawing in 2-mercaptoethanol, the type-2 phosphatase could be stimulated ∼10 fold but surprisingly the type-1 species was not slightly influenced. It is suggested that hormonal study on the activity changes of the type-1 and type-2 phosphatase in a crude extract can be made possible by the selective using of these two triggers.