Binding specificity for RACK1 resides in the V5 region of beta II protein kinase C.
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.
Stebbins
E G
EG
Department of Molecular Pharmacology, Stanford University School of Medicine, Stanford, California 94305-5174, USA.
Mochly-Rosen
D
D
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
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