C-terminal tail phosphorylation of N-formyl peptide receptor: differential recognition of two neutrophil chemoattractant receptors by monoclonal antibodies NFPR1 and NFPR2.
The N-formyl peptide receptor (FPR), a G protein-coupled receptor that binds proinflammatory chemoattractant peptides, serves as a model receptor for leukocyte chemotaxis. Recombinant histidine-tagged FPR (rHis-FPR) was purified in lysophosphatidyl glycerol (LPG) by Ni(2+)-NTA agarose chromatography to >95% purity with high yield. MALDI-TOF mass analysis (>36% sequence coverage) and immunoblotting confirmed the identity as FPR. The rHis-FPR served as an immunogen for the production of 2 mAbs, NFPR1 and NFPR2, that epitope map to the FPR C-terminal tail sequences, 305-GQDFRERLI-313 and 337-NSTLPSAEVE-346, respectively. Both mAbs specifically immunoblotted rHis-FPR and recombinant FPR (rFPR) expressed in Chinese hamster ovary cells. NFPR1 also recognized recombinant FPRL1, specifically expressed in mouse L fibroblasts. In human neutrophil membranes, both Abs labeled a 45-75 kDa species (peak M(r) approximately 60 kDa) localized primarily in the plasma membrane with a minor component in the lactoferrin-enriched intracellular fractions, consistent with FPR size and localization. NFPR1 also recognized a band of M(r) approximately 40 kDa localized, in equal proportions to the plasma membrane and lactoferrin-enriched fractions, consistent with FPRL1 size and localization. Only NFPR2 was capable of immunoprecipitation of rFPR in detergent extracts. The recognition of rFPR by NFPR2 is lost after exposure of cellular rFPR to f-Met-Leu-Phe (fMLF) and regained after alkaline phosphatase treatment of rFPR-bearing membranes. In neutrophils, NFPR2 immunofluorescence was lost upon fMLF stimulation. Immunoblotting approximately 60 kDa species, after phosphatase treatment of fMLF-stimulated neutrophil membranes, was also enhanced. We conclude that the region 337-346 of FPR becomes phosphorylated after fMLF activation of rFPR-expressing Chinese hamster ovary cells and neutrophils.
Department of Microbiology, Montana State University, Bozeman, Montana 59717, USA.
Marcia
M
Riesselman
Heini M
HM
Miettinen
Jeannie M
JM
Gripentrog
Connie I
CI
Lord
Brendan
B
Mumey
Edward A
EA
Dratz
Jamal
J
Stie
Ross M
RM
Taylor
Algirdas J
AJ
Jesaitis
D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000276:immunology; D016466:CHO Cells; D002462:Cell Membrane / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D002633:Chemotaxis / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D002846:Chromatography, Affinity; D006224:Cricetinae; D003412:Cricetulus; D018604:Epitope Mapping; D000939:Epitopes / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D005347:Fibroblasts / Q000276:immunology / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007781:Lactoferrin / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D008246:Lysophospholipids / Q000737:chemistry; D051379:Mice; D018448:Models, Immunological; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000031:analogs & derivatives / Q000737:chemistry / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D009504:Neutrophils / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D017434:Protein Structure, Tertiary / Q000235:genetics; D044042:Receptors, Formyl Peptide / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D018411:Spodoptera
D000911:Antibodies, Monoclonal; D000939:Epitopes; D008246:Lysophospholipids; D044042:Receptors, Formyl Peptide; D011993:Recombinant Fusion Proteins; C026223:lysophosphatidylglycerol; D009240:N-Formylmethionine Leucyl-Phenylalanine; C049813:N-formylmethionyl-leucyl-phenylalanyl-lysine; D007781:Lactoferrin