R9AP, a membrane anchor for the photoreceptor GTPase accelerating protein, RGS9-1

doi:10.1073/pnas.152094799

R9AP, a membrane anchor for the photoreceptor GTPase accelerating protein, RGS9-1

Guang Hu and
Theodore G. Wensel*

Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030

Edited by Lutz Birnbaumer, National Institutes of Health, Research Triangle Park, NC, and approved May 28, 2002 (received for review February 15, 2002)

Abstract

The regulator of G protein signaling (RGS)-9-1⋅G_β5 complex forms the GTPase accelerating protein for G_αt in vertebrate photoreceptors. Although the complex is soluble when expressed in vitro, extraction of the endogenous protein from membranes requires detergents. The detergent extracts contain a complex of RGS9-1, G_β5, G_αt, and a 25-kDa phosphoprotein, R9AP (RGS9-1-Anchor Protein). R9AP is encoded by one intronless gene in both human and mouse. Full or partial cDNA or genomic clones were obtained from mice, cattle, human, zebrafish, and Xenopus laevis. R9AP mRNA was detected only in the retina, and the protein only in photoreceptors. R9AP binds to the N-terminal domain of RGS9-1, and anchors it to the disk membrane via a C-terminal transmembrane helix.

Footnotes

↵ * To whom reprint requests should be addressed. E-mail: twensel{at}bcm.tmc.edu
This paper was submitted directly (Track II) to the PNAS office.
Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession nos. AF480475 and AF483907).
Abbreviations:

RGS,

regulator of G protein signaling;

GAP,

GTPase accelerating protein;

ROS,

rod outer segment;

R9AP,

RGS9-1 anchor protein;

OS,

outer segment;

EST,

expressed sequence tag;

NTA,

nitrilotriacetate;

GST,

glutathione S-transferase;

GFP,

green fluorescent protein