Comparison of stimulation by chemotactic formyl peptide analogs between GTPase activity in neutrophil plasma membranes and granule enzyme release from intact neutrophils.
Stimulation by fMet-Leu-Phe analogs of GTPase activity in plasma membranes from rabbit neutrophils was compared with the stimulation of degranulation in intact neutrophils. All four formyl peptides examined (fMet-Leu-Phe-Phe, fMet-Leu-Phe, fNle-Leu-Phe, and fVal-Leu-Phe) were full agonists for both responses. Their ED50 values for the two responses correlated well, although those for GTPase stimulation were uniformly about tenfold greater. The specific antagonist tBoc-Phe-Leu-Phe-Leu-Phe competitively inhibited both GTPase activity and degranulation stimulated by fMet-Leu-Phe; its Ki values were similar for the two responses. Pertussis toxin treatment, in contrast, inhibited the maximal stimulation of both responses by fMet-Leu-Phe with minimal shift in ED50. The inhibitory actions of tBoc-Phe-Leu-Phe-Leu-Phe and pertussis toxin on GTPase activity thus paralleled the effects on degranulation. These observations substantiate the hypothesis that a guanine nucleotide-binding protein that is a pertussis toxin substrate couples the formyl peptide receptors to physiological function in the neutrophil.
Kanaho
Y
Y
Department of Pathology, University of Connecticut Health Center, Farmington.
Kermode
J C
JC
Becker
E L
EL
D000818:Animals; D015550:Cell Degranulation / Q000187:drug effects* / Q000502:physiology; D002462:Cell Membrane / Q000201:enzymology* / Q000648:ultrastructure; D002630:Chemotactic Factors / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D020558:GTP Phosphohydrolases / Q000097:blood*; D019204:GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000031:analogs & derivatives; D009504:Neutrophils / Q000201:enzymology* / Q000502:physiology / Q000648:ultrastructure; D010744:Phosphoric Monoester Hydrolases / Q000097:blood*; D011817:Rabbits
D002630:Chemotactic Factors; D009240:N-Formylmethionine Leucyl-Phenylalanine; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins