N-formyl peptide receptors, member of the class A family of seven-transmembrane G protein-coupled receptors
The formyl peptide receptors (FPRs) are chemoattractant GPCRs that involved in mediating immune responses to infection. They are expressed at elevated levels on polymorphonuclear and mononuclear phagocytes. FPRs bind N-formyl peptides, which are derived from the mitochondrial proteins of ruptured host cells or invading pathogens. Activation of FPRs by N-formyl peptides such as N-formyl-Met-Leu-Phe (FMLP) triggers a signaling cascade that stimulates neutrophil accumulation, phagocytosis and superoxide production. These responses are mediated through a pertussis toxin-sensitive G(i) protein that activates a PLC-IP3-calcium signaling pathway. While FPRs are involved in host defense responses to bacterial infection, they can also suppress the immune system under certain conditions. Yet, the physiological role of the FPR family is not fully understood.
Comment:based on the structures of some class A family members with bound ligands (peptides or chemicals), agonists, or antagonists
Comment:Small-molecule chemical ligands tend to bind deeper within the receptor core, compared to a peptide ligand neurotensin, which binds towards the extracellular surface of its receptor.
Jiyao W et al.(2023). "The conserved domain database in 2023.",