Regulators of G protein signaling 6 and 7. Purification of complexes with gbeta5 and assessment of their effects on g protein-mediated signaling pathways.
Regulators of G protein signaling (RGS) proteins that contain DEP (disheveled, EGL-10, pleckstrin) and GGL (G protein gamma subunit-like) domains form a subfamily that includes the mammalian RGS proteins RGS6, RGS7, RGS9, and RGS11. We describe the cloning of RGS6 cDNA, the specificity of interaction of RGS6 and RGS7 with G protein beta subunits, and certain biochemical properties of RGS6/beta5 and RGS7/beta5 complexes. After expression in Sf9 cells, complexes of both RGS6 and RGS7 with the Gbeta5 subunit (but not Gbetas 1-4) are found in the cytosol. When purified, these complexes are similar to RGS11/beta5 in that they act as GTPase-activating proteins specifically toward Galpha(o). Unlike conventional G(betagamma) complexes, RGS6/beta5 and RGS7/beta5 do not form heterotrimeric complexes with either Galpha(o)-GDP or Galpha(q)-GDP. Neither RGS6/beta5 nor RGS7/beta5 altered the activity of adenylyl cyclases types I, II, or V, nor were they able to activate either phospholipase C-beta1 or -beta2. However, the RGS/beta5 complexes inhibited beta(1)gamma(2)-mediated activation of phospholipase C-beta2. RGS/beta5 complexes may contribute to the selectivity of signal transduction initiated by receptors coupled to G(i) and G(o) by binding to phospholipase C and stimulating the GTPase activity of Galpha(o).
Posner
B A
BA
Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA.
Gilman
A G
AG
Harris
B A
BA
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular; D020549:GTP Phosphohydrolase Activators / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D020710:RGS Proteins / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology*; D018411:Spodoptera; D014162:Transfection
D020549:GTP Phosphohydrolase Activators; D046911:Macromolecular Substances; D020710:RGS Proteins; C400195:RGS11 protein, human; C400194:RGS6 protein, human; C492039:RGS7 protein, human; D011994:Recombinant Proteins; C485693:Rgs11 protein, mouse; C485692:Rgs6 protein, mouse; C485691:Rgs6 protein, rat; C492038:Rgs7 protein, mouse; C116925:regulator of g-protein signaling 9; D019204:GTP-Binding Proteins