Inhibition of protein kinase C by a peptide conjugate homologous to a domain of the retroviral protein p15E.

Published

Journal Article

Retroviral infection is associated with immunosuppression, which has been shown to be due, in part, to the action of the envelope protein p15E. We studied a synthetic peptide (CKS-17) homologous to a highly conserved domain of the retroviral envelope protein p15E, which, when conjugated to BSA (CKS-17-BSA), can inhibit IL-1- and phorbol ester-mediated responses in cultured murine thymoma cells, and Ca2(+)- and phosphatidylserine-dependent protein kinase C (PKC) activity of cell homogenates. We characterized the mechanism of inhibition of PKC by the peptide. Using PKC purified from rat brain we found that CKS-17-BSA inhibited PKC-catalyzed Ca2(+)- and phosphatidylserine-dependent histone phosphorylation with an estimated ID50 of 4 microM. CKS-17-BSA did not inhibit the catalytic subunit of cAMP-dependent protein kinase. CKS-17-BSA also inhibited the Ca2(+)- and PS-independent activity of a catalytic fragment of PKC that was generated by limited trypsin treatment. However, CKS-17-BSA did not act as a competitive inhibitor of PKC with respect to ATP or phosphoacceptor substrate, despite the similarity between the CKS-17 sequence and substrates and pseudosubstrates of PKC. We conclude that this peptide homologue of a retroviral envelope protein has a novel mechanism of inhibition of PKC.

Full Text

Duke Authors

Cited Authors

  • Gottlieb, RA; Kleinerman, ES; O'Brian, CA; Tsujimoto, S; Cianciolo, GJ; Lennarz, WJ

Published Date

  • October 15, 1990

Published In

Volume / Issue

  • 145 / 8

Start / End Page

  • 2566 - 2570

PubMed ID

  • 2212653

Pubmed Central ID

  • 2212653

International Standard Serial Number (ISSN)

  • 0022-1767

Language

  • eng

Conference Location

  • United States