The interaction of N-formyl peptide chemoattractant receptors with the membrane skeleton is energy-dependent.
Desensitization of N-formyl peptide chemoattractant receptors (FPR) in human neutrophils is thought to be achieved by lateral segregation of receptors and G proteins within the plane of the plasma membrane resulting in an interruption of the signalling cascade. Direct coupling of FPR to membrane skeletal actin appears to be the basis of this process; however, the molecular mechanism is unknown. In this study we investigated the effect of energy depletion on formation of FPR-membrane skeleton complexes. In addition the effect of the protein kinase C inhibitor stauroporine and the phosphatase inhibitor okadaic acid on coupling of FPR to the membrane skeleton was studied. Human neutrophils were desensitized using the photoreactive agonist N-formyl-met-leu-phe-lys-N'-[125I]2(p-azidosalicylamido)ethyl-1,3' - dithiopropionate (fMLFK-[125I]ASD) after ATP depletion with NaF or after incubation with the respective inhibitors. The interaction of FPR with the membrane skeleton was studied by sedimentation of the membrane skeleton-associated receptors in sucrose density gradients. Energy depletion of the cells markedly inhibited the formation of FPR-membrane skeleton complexes. This does not appear to be related to inhibition of protein phosphorylation due to ATP depletion because inhibition of protein kinases and phosphatases had no significant effect on coupling of FPR to the membrane skeleton. We conclude, therefore, that coupling of FPR to the membrane skeleton is an energy-dependent process which does not appear to require modification of the receptor protein by phosphorylation.
Klotz
K N
KN
Department of Microbiology, Montana State University, Bozeman 59717, USA.
Jesaitis
A J
AJ
D000470:Alkaloids / Q000494:pharmacology; D002462:Cell Membrane / Q000648:ultrastructure*; D004734:Energy Metabolism / Q000187:drug effects; D004988:Ethers, Cyclic / Q000494:pharmacology; D006801:Humans; D009504:Neutrophils / Q000737:chemistry* / Q000648:ultrastructure; D019319:Okadaic Acid; D010766:Phosphorylation; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000737:chemistry* / Q000378:metabolism; D018000:Receptors, Peptide / Q000737:chemistry* / Q000378:metabolism; D019311:Staurosporine
D000470:Alkaloids; D004988:Ethers, Cyclic; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D018000:Receptors, Peptide; D019319:Okadaic Acid; D019311:Staurosporine