The fMet-Leu-Phe (fMLP) receptor FMLP locus: 19q13.4 : [§§] or FPRL1 a mouse counterpart of FPRL1R (the peptide ligand Trp-Lys-Tyr-Met-Val-L-Met-NH(2) a synthetic peptide, WKYMVM uPAR epitope uPAR84-95, is an endogenous ligand for FPRL2 and FPRL1) two closely related G-protein coupled receptors interact with viral and bacterial N-formyl peptides, peptides derived from the N-terminal domain of annexin I serve as FPR ligands [3.]; a member of the GPCR family of receptors. A G protein-coupled receptor, receptors that are internalized in an arrestin-independent manner, that mediates phagocytic host cells to the invasion of microorganisms, N-formyl peptide receptor (FPR) is a key modulator of chemotaxis directing granulocytes toward sites of bacterial infections. T-cell-derived lymphokine human leukocyte inhibitory factor (LIF) is a modulator (PT (pertussis toxin) inhibits FMLP-mediated chemotaxis itself), of many important polymorphonuclear (PMN) functions results in an increase of the interleukin-8 (IL-8) mRNA accumulation and a subsequent release of the protein, and specific proinflammatory arachidonic acid (5-LO) product release, and FPRs colocalized with P2Y2 nucleotide receptors. Hypnotics and sedative drugs dose-dependently interfere with these activating pathways, TNF-mediated PMN oxidative priming may also promote oxidant tissue injury stimulated with the chemotactic peptide FMLP in whole blood originates, predominantly from neutrophils. Two chemoattractant receptor inhibitory proteins from Staphylococcus aureus blocks FPR and (FLIPr-SAB1019c, S. aureus-RF122) the N-formylated peptide, an orphan G protein-coupled receptor while FPRL1-expressing cells migrated to picomolar concentrations of WKYMVm, also found (genistein [1.], staurosporin) inhibitor of protein kinase C (bis-indolyl-maleimide, BIM) was effective only in the cytolitic FMLP and did not occur in PMN directly compare FPR levels specifically elicit exocytosis of gelatinase-rich [ch] and vitamin B-12 (secondary granules) binding protein-poor granules. FPR1 (formyl peptide receptor 1) may be the only receptor capable of binding prototype N-formyl peptides a key modulator of chemotaxis directing granulocytes toward sites of bacterial infections.