title: Ric-8 regulation of heterotrimeric G proteins.
abstract: Resistance to inhibitors of cholinesterase 8 proteins (Ric-8A and Ric-8B) collectively bind the four classes of heterotrimeric G protein α subunits. Ric-8A and Ric-8B act as non-receptor guanine nucleotide exchange factors (GEFs) toward the Gα subunits that each binds in vitro and seemingly regulate diverse G protein signaling systems in cells. Combined evidence from worm, fly and mammalian systems has shown that Ric-8 proteins are required to maintain proper cellular abundances of G proteins. Ric-8 proteins support G protein levels by serving as molecular chaperones that promote Gα subunit biosynthesis. In this review, the evidence that Ric-8 proteins act as non-receptor GEF activators of G proteins in signal transduction contexts will be weighed against the evidence supporting the molecular chaperoning function of Ric-8 in promoting G protein abundance. I will conclude by suggesting that Ric-8 proteins may act in either capacity in specific contexts. The field awaits additional experimentation to delineate the putative multi-functionality of Ric-8 towards G proteins in cells.
authors: Department of Pharmacology and Physiology, University of Rochester Medical Center , Rochester, NY, USA. Gregory_tall@urmc.rochester.edu
authors: Gregory G
authors: GG
authors: Tall
mesh_terms: D000818:Animals; D044385:GTP-Binding Protein alpha Subunits / Q000096:biosynthesis; D005786:Gene Expression Regulation; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism*; D021122:Protein Subunits; D015398:Signal Transduction
chemical_list: D044385:GTP-Binding Protein alpha Subunits; D020662:Guanine Nucleotide Exchange Factors; D009687:Nuclear Proteins; D021122:Protein Subunits; C485884:Ric8a protein, mouse; D020962:Heterotrimeric GTP-Binding Proteins
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