INTERACTION OF HUMAN RETINAL RGS WITH G-PROTEIN ALPHA-SUBUNITS

A novel family of RGS proteins negatively regulates signaling via hete rotrimeric G-proteins by accelerating the GTPase activity of G-protein alpha subunits. We have investigated interaction of human retinal RGS protein (hRGSr) with in vitro translated G(alpha) subunits: G(t alpha ), G(i alpha 1), G(o alpha) and G(s alpha). hRGSr binds well to G(t al pha), G(i alpha 1) and G(o alpha) in the presence of AlF4-, but does n ot interact with G(s alpha). The N- and C-terminally truncated G(alpha ) subunits interact with hRGSr similarly to the intact G(alpha) polype ptides. Analysis of interaction between hRGSr and G(o alpha)/G(s alpha ) chimeras suggests that a region of G(o alpha), G(o alpha)22-212, con tains major structural determinants for binding to RGS proteins. (C) 1 997 Federation of European Biochemical Societies.