CD16a; low affinity immunoglobulin gamma Fc region receptor III-A; IgG Fc receptor III-2; Fc-gamma RIII-alpha; Fc-gamma RIIIa; FcRIIIa; Fc-gamma RIII; FcRIII; FcR-10; CD16a antigen (FCGR3A, CD16A, FCG3, FCGR3, IGFR3)

Function

• low-affinity receptor for the Fc region of IgG
• binds complexed or aggregated IgG & also monomeric IgG
• mediates antibody-dependent cellular cytotoxicity (ADCC) & other antibody-dependent responses, including phagocytosis
• exists as a hetero-oligomeric receptor complex with Fc epsilon receptor 1-gamma &/or CD3-zeta
• interacts with INPP5D/SHIP1 (putative)

Structure

• glycosylated; contains
  • high-mannose oligosaccharides
  • complex-type oligosaccharides
• contains 2 Ig-like C2-type domain (immunoglobulin-like)

Compartment

• cell membrane
• secreted, soluble receptor produced by a proteolytic cleavage

Expression

• NK cells ~10-20%
• granulocytes
• monocytes (rare)
• alveolar macrophages (common)
• subpopulation of T cells
• immature thymocytes
• placental trophoblasts

Pathology

• cells in myelodysplastic syndrome stain negatively with antibody

Genetics

• encoded by one of two nearly indentical genes: FCGR3A & FCGR3B with tissue-specific expression
• the Phe-203 in FCGR3A determines the transmembrane domains
• the Ser-203 in FCGR3B determines the GPI-anchoring

Polymorphism

• isoform Val-157 shows a higher binding capacity of IgG1, IgG3 & IgG4 compared with isoform Phe-157
• alleles Leu-66 & Phe-157, & alleles His-66/Arg-66 & Val-157 are in linkage disequilibrium

More general terms

• CD16, Fc gamma receptor III or Fc gamma receptor (low affinity)

Database

• UniProt: http://www.uniprot.org/uniprot/P08637.html
• OMIM: https://mirror.omim.org/entry/146740