Identification of a Major Protein Kinase C-binding Protein and Substrate in Rat Embryo Fibroblasts

doi:10.1074/jbc.271.11.6417

Identification of a Major Protein Kinase C-binding Protein and Substrate in Rat Embryo Fibroblasts

DECREASED EXPRESSION IN TRANSFORMED CELLS (*)

From the W. Alton Jones Cell Science Center, Inc., Lake Placid, New York 12946

^§To whom correspondence should be addressed:
W. Alton Jones Cell Science Center, Inc., 10 Old Barn Rd., Lake Placid, NY 12946.
Tel.: 518-523-1260; Fax: 518-523-1849; jakenlab{at}ns.cencom.net.

Abstract

We have used an interaction cloning strategy to isolate cDNAs for sequences that interact with protein kinase C (Chapline, C., Ramsay, K., Klauck, T., and Jaken, S.(1993) J. Biol. Chem. 268, 6858-6861). In this paper, we report a novel sequence, clone 72, isolated according to this method. Clone 72 has a 4.8-kilobase pair open reading frame; antibodies to clone 72 recognize a >200-kDa protein in cell and tissue extracts. Clone 72 message and protein are detected in a variety of tissues. Immunoprecipitation studies demonstrate that clone 72 is the major >200-kDa binding protein described previously in REF52 fibroblasts (Hyatt, S. L., Liao, L., Aderem, A., Nairn, A., and Jaken, S.(1994) Cell Growth & Differ. 5, 495-502). Expression of clone 72 message and protein are decreased in progressively transformed REF52 cells. Since clone 72 is both a protein kinase C (PKC)-binding protein and substrate, decreased levels of clone 72 may influence both the subcellular location of endogenous PKCs as well as signaling events associated with clone 72 phosphorylation. Our results emphasize that the role of PKCs in carcinogenesis may involve several factors, including the quantity and location of the PKCs isozymes and their downstream targets.

Footnotes

↵* This work was supported by National Institutes of Health Grants CA53841 and GM50152 (to S. J.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

PKC

protein kinase C

RACE

rapid amplification of cDNA ends

PCR

polymerase chain reaction

bp

base pair(s)

kb

kilobase pair(s)

MARCKS

myristoylated alanine-rich C kinase substrate.
↵²I. Gelman, personal communication.
- Received August 31, 1995.
- Revision received November 20, 1995.