Dephosphorylation of perilipin by protein phosphatases present in rat adipocytes

By incubating 32P-labelled adipocytes, and extracts from these cells, in the presence or absence of specific inhibitors, we evaluated the contribution of protein phosphatases PP1, PP2A and PP2C, to the dephosphorylation of perilipin, an acutely hormone-regulated adipocyte phosphoprotein. Under conditions to completely inhibit PP2A activity, perilipin phosphatase activity in extracts remain unaffected, but PP1 inhibition results in abolition of perilipin phosphatase activity. Inhibition of PP1 (and 2A) in intact adipocytes stimulated lipolysis and increased phosphorylation of perilipin. No involvement of PP2C was found. Hence, PP1 constitutes the predominant if not sole perilipin phosphatase in adipocytes.