Initial observations of a kallikrein-like enzyme associated with the plasma membranes of rat adipocytes.

Abstract

Homogenates of rat adipocytes and plasma membranes thereof were shown by radioimmunoassay to contain immunoreactive glandular kallikrein. On the basis of the hydrolysis of D-Val-Leu-Arg-p-nitroanilide, the kallikrein-like enzyme associated with the plasma membranes was found not to be stimulated by prior incubation with melittin or phospholipase A2. However, pre-incubation of the membrane preparation with trypsin did increase the activity of the enzyme. Furthermore, activation could also be achieved by incubating the plasma membranes with insulin at a dose that stimulated glucose uptake into intact adipocytes. On the other hand, incubation with insulin at a dose that did not increase glucose uptake into rat adipocytes was ineffective in activating the kallikrein-like enzyme.