The Coatomer Protein β′-COP, a Selective Binding Protein (RACK) for Protein Kinase Cε*
- From the ‡Department of Molecular Pharmacology, Stanford University School of Medicine, Stanford, California 94305-5332 and the §Department of Cell Biology and Oncology, Consorzio Mario Negri SUD, 66030 Santa Maria Imbaro (Chieti), Italy
Abstract
Distinct subcellular localization of activated protein kinase C (PKC) isozymes is mediated by their binding to isozyme-specific RACKs (receptors for activatedC-kinase). Our laboratory has previously isolated one such protein, RACK1, and demonstrated that this protein displays specificity for PKCβ. We have recently shown that at least part of the PKCε RACK-binding site on PKCε lies within the unique V1 region of this isozyme (Johnson, J. A., Gray, M. O., Chen, C.-H., and Mochly-Rosen, D. (1996) J. Biol. Chem. 271, 24962–24966). Here, we have used the PKCε V1 region to clone a PKCε-selective RACK, which was identified as the COPI coatomer protein, β′-COP. Similar to RACK1, β′-COP contains seven repeats of the WD40 motif and fulfills the criteria previously established for RACKs. Activated PKCε colocalizes with β′-COP in cardiac myocytes and binds to Golgi membranes in a β′-COP-dependent manner. A role for PKC in control of secretion has been previously suggested, but this is the first report of direct protein/protein interaction of PKCε with a protein involved in vesicular trafficking.
Footnotes
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↵* This work was supported by grants from the Consiglio Nazionale delle Ricerche (to M. A. D. M.) and by Grant HL52141 from the National Institutes of Health (to D. M.-R.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵¶ To whom correspondence should be addressed. Tel.: 650-725-7720; Fax: 650-725-2952.
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↵1 The abbreviations used are: PKC, protein kinase C; RACE, rapid amplification of cDNA ends; MBP, maltose-binding protein; PS, phosphatidylserine; DG, diacylglycerol; PAGE, polyacrylamide gel electrophoresis; GTPγS, guanosine 5′-O-(3-thiotriphosphate); ARF, ADP-ribosylation factor; BFA, brefeldin A.
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↵2 M. M. Rodriguez and D. Mochly-Rosen, unpublished observation.
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- Received September 9, 1997.
