FPR3 may function as a pattern recognition G protein-coupled receptor involved in innate recognition of peptides derived from a specific set of bacterial pathogens, or from host mitochondria, which act as pathogen- and damage-associated molecular patterns. It is a low affinity receptor for a restricted repertoire of bacterial N-formylated peptides, including fMKKIML from L. monocytogenes and fMPKLNR from V. cholerae. Unlike FPR1 and FPR2, it does not act as a receptor for the fMLF peptide.

The receptor also recognises host-derived peptides. It is a high affinity receptor for the N-acetylated F2L peptide, released by cleavage of heme-binding protein HEBP1, and F2L binding may trigger chemotaxis of monocytes and dendritic cells to facilitate tissue repair. It is a low affinity receptor for Ac2-26, an N-acetylated peptide from ANXA1 with anti-inflammatory and pro-resolving activity. Ac2-26 can direct myeloid cell chemotaxis within the inflammatory site, but can also cause receptor desensitisation that limits the inflammatory response. FPR3 is further a receptor for humanin (MT-RNR2), a mitochondrial-derived peptide with an anti-inflammatory role in the resolution of inflammation.

Peptide binding causes conformational changes coupled to heterotrimeric G(i) signalling. After GDP to GTP exchange, the G(i)-alpha subunit dissociates from the G-beta/G-gamma dimer. Free G(i)-alpha inhibits adenylate cyclase and cAMP synthesis, while G-beta/G-gamma activates phospholipase C-beta and phosphoinositide 3-kinase cascades, leading to Ca(2+) influx. NCBI Gene annotation predicts N-formyl peptide receptor and complement receptor activity, and places the protein in the plasma membrane. The FPR3 gene was formerly named formyl peptide receptor-like 2 (FPRL2). The mouse ortholog is Fpr-s1. FPR3 belongs to the G protein-coupled receptor 1 family.