The GTPase Activating Factor for Transducin in Rod Photoreceptors Is the Complex between RGS9 and Type 5 G Protein β Subunit

• Published in: Proceedings of the National Academy of Sciences - PNAS 1999-03, Vol.96 (5), p.1947-1952
• Main Authors: Makino, Elina R., Handy, Jason W., Li, Tiansen, Arshavsky, Vadim Y.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Antibodies; Biochemistry; Biological Sciences; Chromatography; Complementary DNA; Epitopes - chemistry; Gels; GTP Phosphohydrolases - metabolism; GTP-Binding Proteins - chemistry; GTP-Binding Proteins - isolation & purification; GTP-Binding Proteins - metabolism; GTPase-Activating Proteins; HEK293 cells; Macromolecular Substances; Mass Spectrometry; Molecular Sequence Data; Photoreceptors; Plasmids; Protein Binding; Proteins; Proteins - chemistry; Proteins - isolation & purification; Proteins - metabolism; ras GTPase-Activating Proteins; ras Proteins - metabolism; RGS proteins; Rhodopsin - metabolism; Rod Cell Outer Segment - metabolism; Transducin - isolation & purification; Transducin - metabolism; Vertebrates
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.96.5.1947

Proteins of the regulators of G protein signaling (RGS) family modulate the duration of intracellular signaling by stimulating the GTPase activity of G protein α subunits. It has been established that the ninth member of the RGS family (RGS9) participates in accelerating the GTPase activity of the photoreceptor-specific G protein, transducin. This process is essential for timely inactivation of the phototransduction cascade during the recovery from a photoresponse. Here we report that functionally active RGS9 from vertebrate photoreceptors exists as a tight complex with the long splice variant of the G protein β subunit (Gβ 5L). RGS9 and Gβ 5Lalso form a complex when coexpressed in cell culture. Our data are consistent with the recent observation that several RGS proteins, including RGS9, contain G protein γ -subunit like domain that can mediate their association with Gβ 5(Snow, B. E., Krumins, A. M., Brothers, G. M., Lee, S. F., Wall, M. A., Chung, S., Mangion, J., Arya, S., Gilman, A. G. & Siderovski, D. P. (1998) Proc. Natl. Acad. Sci. USA 95, 13307-13312). We report an example of such a complex whose cellular localization and function are clearly defined.