Accessory proteins for G protein-signaling systems: activators of G protein signaling and other nonreceptor proteins influencing the activation state of G proteins.
Heterotrimeric G proteins are key transducers for signal transfer from outside of the cell. In addition to their regulation by the superfamily of G protein-coupled receptors, many if not all of the subtypes of heterotrimeric G proteins are also regulated by additional accessory proteins that influence guanine nucleotide binding and/or hydrolysis or subunit interactions. Activators of G protein signaling (AGS1-3) refer to a functionally defined group of proteins that activate G protein-signaling systems in the absence of a classical G protein-coupled receptor. AGS and related proteins provide unexpected insights into the regulation of the G protein activation/deactivation cycle and the functional roles of G proteins. These proteins likely play important roles in the generation of signaling complexes, the positioning of signaling proteins within the cell, and in biological roles of G proteins unrelated to a cell surface receptor. As such, these proteins and the concepts advanced with their discovery provide unexpected avenues for therapeutics and understanding disease mechanisms.
Blumer
Joe B
JB
Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70118, USA.
Lanier
Stephen M
SM
D000818:Animals; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D015398:Signal Transduction / Q000502:physiology*
D020962:Heterotrimeric GTP-Binding Proteins