DEPHOSPHORYLATION OF PERILIPIN BY PROTEIN PHOSPHATASES PRESENT IN RATADIPOCYTES

By incubating P-32-labelled adipocytes, and extracts from these cells, in the presence or absence of specific inhibitors, we evaluated the c ontribution of protein phosphatases PP1, PP2A and PP2C, to the dephosp horylation of perilipin, an acutely hormone-regulated adipocyte phosph oprotein. Under conditions to completely inhibit PP2A activity, perili pin phosphatase activity in extracts remain unaffected, but PP1 inhibi tion results in abolition of perilipin phosphatase activity. Inhibitio n of PP1 (and 2A) in intact adipocytes stimulated lipolysis and increa sed phosphorylation of perilipin. No involvement of PP2C was found. He nce, PP1 constitutes the predominant if not sole perilipin phosphatase in adipocytes. (C) 1998 Federation of European Biochemical Societies.