Mechanisms Governing Subcellular Localization and Function of Human RGS2

Scott P. Heximer, Han Lim, Jennifer L. Bernard, Kendall J. Blumer

Research output: Contribution to journalArticle

104 Scopus citations

Abstract

RGS proteins negatively regulate heterotrimeric G proteins at the plasma membrane. RGS2-GFP localizes to the nucleus, plasma membrane, and cytoplasm of HEK293 cells. Expression of activated Gq increased RGS2 association with the plasma membrane and decreased accumulation in the nucleus, suggesting that signal-induced redistribution may regulate RGS2 function. Thus, we identified and characterized a conserved N-terminal domain in RGS2 that is necessary and sufficient for plasma membrane localization. Mutational and biophysical analyses indicated that this domain is an amphipathic α-helix that binds vesicles containing acidic phospholipids. However, the plasma membrane targeting function of the amphipathic helical domain did not appear to be essential for RGS2 to attenuate signaling by activated Gq. Nevertheless, truncation mutants indicated that the N terminus is essential, potentially serving as a scaffold that binds receptors, signaling proteins, or nuclear components. Indeed, the RGS2 N terminus directs nuclear accumulation of GFP. Although RGS2 possesses a nuclear targeting motif, it lacks a nuclear import signal and enters the nucleus by passive diffusion. Nuclear accumulation of RGS2 does not limit its ability to attenuate Gq signaling, because excluding RGS2 from the nucleus was without effect. RGS2 may nonetheless regulate signaling or other processes in the nucleus.

Original languageEnglish
Pages (from-to)14195-14203
Number of pages9
JournalJournal of Biological Chemistry
Volume276
Issue number17
DOIs
StatePublished - Apr 27 2001
Externally publishedYes

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