FKBP, the Binding Protein for the Immunosuppressive Drug, FK-506, Is Not an Inhibitor of Protein Kinase C Activity
Recently, the amino acid sequence of a 12 Kd endogenous protein inhibitor of protein kinase C (PKC-I 2) has been shown to be identical to that of the 12 KDa receptor for the immunosuppressive drug, FK-506. In view of this observation we examined the effects of recombinant and native human FKBP on protein kinase C (PKC) activity. FKBP, at molar concentrations up to 1900-fold over that of PKC, failed to inhibit PKC phosphorylation of histone H1 and failed to block the auto-phosphorylation of PKC. Interestingly, FKBP is phosphorylated by PKC in these reactions. The phosphorylation of FKBP by PKC appears to be specific since the catalytic subunit of cAMP-dependent protein kinase fails to phosphorylate the binding protein. Our results fail to support a role for FKBP as an inhibitor of protein kinase C.
MSU Digital Commons Citation
Cryan, John G.; Hung, Shirley H Y; Wiederrecht, Gregory; Sigal, Nolan H.; and Siekierka, John, "FKBP, the Binding Protein for the Immunosuppressive Drug, FK-506, Is Not an Inhibitor of Protein Kinase C Activity" (1991). Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works. 249.