Role of Sst2 in modulating G protein-coupled receptor signaling.
Sst2 formally acts as an inhibitor of G protein-coupled receptor signaling in yeast perhaps stabilizing a G protein/unactivated receptor complex. desTrp1,Ala3 alpha-factor (dTA-alpha f), normally a competitive antagonist, activated responses in an sst2 strain. The antagonist to agonist switch was consistent with an Sst2 effect on receptor/G protein coupling, but not with an Sst2 role in global reduction of signaling. Response to alpha-factor, assayed by growth arrest, was independent of level of expressed surface receptor over a 40-fold range in an SST2+ strain, consistent with coupling of only a subset of receptors to G protein. In contrast, in an sst2 strain response to alpha-factor was proportional to receptor expression, consistent with participation of all receptors in signaling. The wt alpha-factor receptor inhibited signaling in response to dTA-alpha f when introduced into a CKC4 chimeric receptor strain. The dominant-negative effect of the receptor might reflect sequestration of G protein.
Shah
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A
Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Marsh
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L
D005656:Fungal Proteins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D005799:Genes, Dominant; D008024:Ligands; D010455:Peptides / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D020710:RGS Proteins
D005656:Fungal Proteins; D019204:GTP-Binding Proteins; D020690:GTPase-Activating Proteins; D008024:Ligands; D010455:Peptides; D011956:Receptors, Cell Surface; D029701:Saccharomyces cerevisiae Proteins; C094301:SST2 protein, S cerevisiae; D020710:RGS Proteins