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

J Biol Chem. 1990 Mar 15;265(8):4507-14.


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.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Brain Chemistry
  • Cattle
  • Erythrocytes / analysis
  • GTP Phosphohydrolases / metabolism
  • GTP-Binding Proteins / isolation & purification
  • GTP-Binding Proteins / metabolism*
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Guanosine Diphosphate / metabolism
  • Guanosine Triphosphate / analogs & derivatives
  • Guanosine Triphosphate / metabolism
  • Humans
  • Kinetics
  • Molecular Weight
  • Pituitary Gland / analysis
  • Receptors, Dopamine / isolation & purification
  • Receptors, Dopamine / metabolism*
  • Receptors, Dopamine D2
  • Rhodopsin / metabolism
  • Signal Transduction
  • Thionucleotides / metabolism


  • Receptors, Dopamine
  • Receptors, Dopamine D2
  • Thionucleotides
  • Guanosine Diphosphate
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Guanosine Triphosphate
  • Rhodopsin
  • GTP Phosphohydrolases
  • GTP-Binding Proteins