The Coatomer Protein β′-COP, a Selective Binding Protein (RACK) for Protein Kinase Cε

• Published in: The Journal of biological chemistry 1997-11, Vol.272 (46), p.29200-29206
• Main Authors: Csukai, Michael, Chen, Che-Hong, De Matteis, Maria Antonietta, Mochly-Rosen, Daria
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.272.46.29200

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.