CD64 (biology)

CD64 (Cluster of Differentiation 64) is a type of integral membrane glycoprotein known as an Fc receptor that binds monomeric IgG-type antibodies with high affinity.[1] It is more commonly known as Fc-gamma receptor 1 (FcγRI). After binding IgG, CD64 interacts with an accessory chain known as the common γ chain (γ chain), which possesses an ITAM motif that is necessary for triggering cellular activation.[2]

Fc fragment of IgG, high affinity Ia, receptor (CD64)
Identifiers
SymbolFCGR1A
NCBI gene2209
HGNC3613
OMIM146760
RefSeqNM_000566
UniProtP12314
Other data
LocusChr. 1 q21.2-21.3
Fc fragment of IgG, high affinity Ib, receptor (CD64)
Identifiers
SymbolFCGR1B
NCBI gene2210
HGNC3614
OMIM601502
RefSeqNM_001004340
UniProtQ92637
Other data
LocusChr. 1 p11.2
Fc fragment of IgG, high affinity Ic, receptor (CD64)
Identifiers
SymbolFCGR1C
NCBI gene2211
HGNC3615
OMIM601503
RefSeqXM_001133198
Other data
LocusChr. 1 q21.1

Structurally CD64 is composed of a signal peptide that allows its transport to the surface of a cell, three extracellular immunoglobulin domains of the C2-type that it uses to bind antibody, a hydrophobic transmembrane domain, and a short cytoplasmic tail.[3]

CD64 is constitutively found on only macrophages and monocytes, but treatment of polymorphonuclear leukocytes with cytokines like IFNγ and G-CSF can induce CD64 expression on these cells.[4][5]

There are three distinct (but highly similar) genes in humans for CD64 called FcγRIA (CD64A), FcγRIB (CD64B), and FcγRIC (CD64C) that are located on chromosome 1.[6] These three genes produce six different mRNA transcripts; two from CD64A, three from CD64B, and one from CD64C; by alternate splicing of the genes.[3]

References
  1. Hulett M, Hogarth P (1998). "The second and third extracellular domains of FcgammaRI (CD64) confer the unique high affinity binding of IgG2a". Mol Immunol. 35 (14–15): 989–96. doi:10.1016/S0161-5890(98)00069-8. PMID 9881694.
  2. Nimmerjahn F, Ravetch J (2006). "Fcgamma receptors: old friends and new family members". Immunity. 24 (1): 19–28. doi:10.1016/j.immuni.2005.11.010. PMID 16413920.
  3. Ernst L, Duchemin A, Miller K, Anderson C (1998). "Molecular characterization of six variant Fcgamma receptor class I (CD64) transcripts". Mol Immunol. 35 (14–15): 943–54. PMID 9881690.
  4. Perussia B, Dayton E, Lazarus R, Fanning V, Trinchieri G (1983). "Immune interferon induces the receptor for monomeric IgG1 on human monocytic and myeloid cells". J Exp Med. 158 (4): 1092–113. doi:10.1084/jem.158.4.1092. PMC 2187379. PMID 6225822.
  5. Repp R, Valerius T, Sendler A, Gramatzki M, Iro H, Kalden J, Platzer E (1991). "Neutrophils express the high affinity receptor for IgG (Fc gamma RI, CD64) after in vivo application of recombinant human granulocyte colony-stimulating factor". Blood. 78 (4): 885–9. PMID 1714327.
  6. Ernst L, van de Winkel J, Chiu I, Anderson C (1992). "Three genes for the human high affinity Fc receptor for IgG (Fc gamma RI) encode four distinct transcription products". J Biol Chem. 267 (22): 15692–700. PMID 1379234.
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