title: Binding specificity for RACK1 resides in the V5 region of beta II protein kinase C.
abstract: Identification of selective anchoring proteins responsible for specialized localization of specific signaling proteins has led to the identification of new inhibitors of signal transduction, inhibitors of anchoring protein-ligand interactions. RACK1, the first receptor for activated C kinase identified in our lab, is a selective anchoring protein for betaII protein kinase C (betaIIPKC). We previously found that at least part of the RACK1-binding site resides in the C2 domain of betaIIPKC (Ron, D., Luo, J., and Mochly-Rosen, D. (1995) J. Biol. Chem. 270, 24180-24187). Here we show that the V5 domain also contains part of the RACK1-binding site in betaIIPKC. In neonatal rat cardiac myocytes, the betaIIV5-3 peptide (amino acids 645-650 in betaIIPKC) selectively inhibited phorbol 12-myristate 13-acetate (PMA)-induced translocation of betaIIPKC and not betaIPKC. In addition, the betaIIV5-3 peptide inhibited cardiac myocyte hypertrophy in PMA-treated cells. Interestingly, betaIV5-3 (646-651 in betaIPKC), a selective translocation inhibitor of betaIPKC, also inhibited PMA-induced cardiac myocyte hypertrophy, demonstrating that both betaI- and betaIIPKC are essential for this cardiac function. Therefore, the betaIIV5 domain contains part of the RACK1-binding site in betaIIPKC; a peptide corresponding to this site is a selective inhibitor of betaIIPKC and, hence, enables the identification of betaIIPKC-selective functions.
authors.affiliation: Department of Molecular Pharmacology, Stanford University School of Medicine, Stanford, California 94305-5174, USA.
authors.forename: E G
authors.initials: EG
authors.lastname: Stebbins
authors.forename: D
authors.initials: D
authors.lastname: Mochly-Rosen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D001665:Binding Sites; D001667:Binding, Competitive; D015153:Blotting, Western; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins; D005982:Glutathione Transferase / Q000378:metabolism; D007527:Isoenzymes / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009206:Myocardium / Q000166:cytology; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D010649:Phenylalanine / Q000378:metabolism; D011485:Protein Binding; D011493:Protein Kinase C / Q000737:chemistry*; D064546:Protein Kinase C beta; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; D009363:Neoplasm Proteins; D010455:Peptides; C419368:RACK1 protein, human; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D010649:Phenylalanine; D005982:Glutathione Transferase; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate