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Title: A retroviral-derived peptide phosphorylates protein kinase D/protein kinase Cμ involving phospholipase C and protein kinase C u_net
Authors: Voravich Luangwedchakarn
Noorbibi K. Day
Remi Hitchcock
Pam G. Brown
Danica L. Lerner
Rajivi P. Rucker
George J. Cianciolo
Robert A. Good
Soichi Haraguchi
University of South Florida St. Petersburg
Duke University School of Medicine
Mahidol University
Keywords: Biochemistry, Genetics and Molecular Biology;Neuroscience
Issue Date: 1-May-2003
Citation: Peptides. Vol.24, No.5 (2003), 631-637
Abstract: CKS-17, a synthetic peptide representing a unique amino acid motif which is highly conserved in retroviral transmembrane proteins and other immunoregulatory proteins, induces selective immunomodulatory functions, both in vitro and in vivo, and activates intracellular signaling molecules such as cAMP and extracellular signal-regulated kinases. In the present study, using Jurkat T-cells, we report that CKS-17 phosphorylates protein kinase D (PKD)/protein kinase C (PKC) μ. Total cell extracts from CKS-17-stimulated Jurkat cells were immunoblotted with an anti-phospho-PKCμ antibody. The results show that CKS-17 significantly phosphorylates PKD/PKCμ in a dose- and time-dependent manner. Treatment of cells with the PKC inhibitors GF 109203X and Ro 31-8220, which do not act directly on PKD/PKCμ, attenuates CKS-17-induced phosphorylation of PKD/PKCμ. In contrast, the selective protein kinase A inhibitor H-89 does not reverse the action of CKS-17. Furthermore, a phospholipase C (PLC) selective inhibitor, U-73122, completely blocks the phosphorylation of PKD/PKCμ by CKS-17 while a negative control U-73343 does not. In addition, substitution of lysine for arginine residues in the CKS-17 sequence completely abrogates the ability of CKS-17 to phosphorylate PKD/PKCμ. These results clearly indicate that CKS-17 phosphorylates PKD/PKCμ through a PLC- and PKC-dependent mechanism and that arginine residues play an essential role in this activity of CKS-17, presenting a novel modality of the retroviral peptide CKS-17 and molecular interaction of this compound with target cells. © 2003 Elsevier Inc. All rights reserved.
ISSN: 01969781
Appears in Collections:Scopus 2001-2005

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