Identification of a Novel Protein Kinase A Anchoring Protein That Binds Both Type I and Type II Regulatory Subunits

doi:10.1074/jbc.272.12.8057

Identification of a Novel Protein Kinase A Anchoring Protein That Binds Both Type I and Type II Regulatory Subunits*

From the ^‡ Department of Chemistry and Biochemistry and the
^∥ Department of Pharmacology and Neuroscience Program, School of Medicine, University of California, San Diego, La Jolla, California 92093-0654

^‡‡ To whom correspondence should be addressed:
Dept. of Chemistry and Biochemistry, School of Medicine, University of California, San Diego, 9500 Gilman Dr. 0654, La Jolla, CA 92093-0654.
Tel.: 619-534-3677; Fax: 619-534-8193; E-mail: staylor{at}ucsd.edu

Abstract

Compartmentalization of cAMP-dependent protein kinase is achieved in part by interaction with A-kinase anchoring proteins (AKAPs). All of the anchoring proteins identified previously target the kinase by tethering the type II regulatory subunit. Here we report the cloning and characterization of a novel anchoring protein, D-AKAP1, that interacts with the N terminus of both type I and type II regulatory subunits. A novel cDNA encoding a 125-amino acid fragment of D-AKAP1 was isolated from a two-hybrid screen and shown to interact specifically with the type I regulatory subunit. Although a single message of 3.8 kilobase pairs was detected for D-AKAP1 in all embryonic stages and in most adult tissues, cDNA cloning revealed the possibility of at least four splice variants. All four isoforms contain a core of 526 amino acids, which includes the R binding fragment, and may be expressed in a tissue-specific manner. This core sequence was homologous to S-AKAP84, including a mitochondrial signal sequence near the amino terminus (Lin, R. Y., Moss, S. B., and Rubin, C. S. (1995) J. Biol. Chem. 270, 27804-27811). D-AKAP1 and the type I regulatory subunit appeared to have overlapping expression patterns in muscle and olfactory epithelium by in situ hybridization. These results raise a novel possibility that the type I regulatory subunit may be anchored via anchoring proteins.

Footnotes

↵^§ Supported by UCSD Cell Molecular and Genetics Training Grant 2T32GM07240-21A1.
↵^¶ Supported by the Markey Charitable Trust as a Fellow and is currently supported by NIH Training Grant NCI T32 CA09523.
↵** Supported by a National Science Foundation graduate fellowship.
↵* This work was supported in part by American Cancer Society Grant BE-48L (to S. S. T.) and National Institutes of Health (NIH) Grant R29MH51699 (to J. C.). 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.
↵¹ The abbreviations used are:

PKA

cAMP-dependent protein kinase

AKAP

A-kinase anchoring protein

R subunit

cAMP-dependent protein kinase regulatory subunit

C subunit

cAMP-dependent protein kinase catalytic subunit

R^I

type Iα

regulatory subunit of cAMP-dependent protein kinase; R^II

type IIα

regulatory subunit of cAMP-dependent protein kinase; PAGE

polyacrylamide gel electrophoresis

GST

glutathione S-transferase

PBS

phosphate-buffered saline.
- Received August 28, 1996.
- Revision received January 15, 1997.