Specificity of receptor-G protein interactions. Discrimination of Gi subtypes by the D2 dopamine receptor in a reconstituted system.

Journal Article (Journal Article)

The selectivity of D2 dopamine receptor-guanine nucleotide-binding protein (G protein) coupling was studied by reconstitution techniques utilizing purified D2 dopamine receptors from bovine anterior pituitary and resolved G proteins from bovine brain, bovine pituitary, and human erythrocyte. Titration of a fixed receptor concentration with varying G protein concentrations revealed two aspects of receptor-G protein coupling. First, Gi2 appeared to couple selectively with the D2 receptor with approximately 10-fold higher affinity than any other tested Gi subtype. Second, the G proteins differed in the maximal receptor-mediated agonist stimulation of the intrinsic GTPase activity. Gi2 appeared to be maximally stimulated by agonist-receptor complex with turnover numbers of approximately 2 min-1. The other Gi subtypes, Gi1 and Gi3, could be only partially activated, resulting in maximal rates of GTPase of approximately 1 min-1. Agonist-stimulated GTPase activity was not detected in preparations containing Go from bovine brain. The differences in maximal agonist-stimulated GTPase rates observed among the Gi subtypes could be explained by differences in agonist-promoted guanyl nucleotide exchange. Both guanosine 5'-3-O-(thio)triphosphate (GTP gamma S) binding and GDP release parameters were enhanced 2-fold for the Gi2 subtype over the other Gi subtypes. These results suggest that even though several types of pertussis toxin substrate may exist in most tissues, a receptor may interact discretely with G proteins, thereby dictating signal transduction mechanisms.

Full Text

Duke Authors

Cited Authors

  • Senogles, SE; Spiegel, AM; Padrell, E; Iyengar, R; Caron, MG

Published Date

  • March 15, 1990

Published In

Volume / Issue

  • 265 / 8

Start / End Page

  • 4507 - 4514

PubMed ID

  • 2137824

International Standard Serial Number (ISSN)

  • 0021-9258


  • eng

Conference Location

  • United States