Chemoattractant receptor-specific differences in G protein activation rates regulate effector enzyme and functional responses

J Leukoc Biol. 1995 Apr;57(4):679-86. doi: 10.1002/jlb.57.4.679.

Abstract

The hypothesis that disparate neutrophil functional responses to various chemoattractants are regulated by receptor-specific rates of G protein activation was examined in HL-60 granulocytes. The initial rates of G protein activation and the affinity of receptor-stimulated G proteins for GTP gamma S in HL-60 membranes stimulated by fMet-Leu-Phe, C5a, and leukotriene B4 (LTB4) differed significantly among the chemoattractants, with a rank order of fMet-Leu-Phe > C5a > LTB4. Equilibrium GTP gamma S binding showed that all three chemoattractants activated a common pool of G proteins. Stimulation of phospholipase D activation, measured as phosphatidylethanol generation, and superoxide release in intact cells also occurred with a rank order of fMet-Leu-Phe > C5a > LTB4. On the other hand, the rank order of receptor affinities for ligand and of the EC50 of chemoattractant stimulation of GTP gamma S binding was C5a > LTB4 > fMet-Leu-Phe. C5a and LTB4 receptor densities were similar but were less than formyl peptide receptor density. Graded pertussis toxin treatment proportionally reduced superoxide release and phospholipase D activation to all three chemoattractants. The results suggest that receptor-specific differences in G protein affinity for guanine nucleotides lead to different rates of guanine nucleotide exchange and, thereby, contribute to disparate effector enzyme and functional responses.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Chemotactic Factors / metabolism
  • Chemotactic Factors / pharmacology
  • Enzyme Activation
  • GTP-Binding Proteins / metabolism
  • GTP-Binding Proteins / physiology*
  • Granulocytes / drug effects
  • Granulocytes / physiology
  • Granulocytes / ultrastructure
  • Guanosine 5'-O-(3-Thiotriphosphate) / metabolism
  • Humans
  • Kinetics
  • Leukemia, Myeloid
  • Molecular Sequence Data
  • N-Formylmethionine Leucyl-Phenylalanine / metabolism
  • N-Formylmethionine Leucyl-Phenylalanine / pharmacology
  • Phospholipase D / drug effects
  • Phospholipase D / metabolism*
  • Phospholipase D / physiology
  • Receptors, Formyl Peptide
  • Receptors, Immunologic / drug effects
  • Receptors, Immunologic / metabolism
  • Receptors, Immunologic / physiology*
  • Receptors, Peptide / drug effects
  • Receptors, Peptide / metabolism
  • Receptors, Peptide / physiology*
  • Stimulation, Chemical
  • Substrate Specificity

Substances

  • Chemotactic Factors
  • Receptors, Formyl Peptide
  • Receptors, Immunologic
  • Receptors, Peptide
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • N-Formylmethionine Leucyl-Phenylalanine
  • Phospholipase D
  • GTP-Binding Proteins