|CD16a||FCγRIIIA (Fc fragment of IgG low affinity IIIa receptor), FCGRIIIA|
|Molecule Type||Antigen Expression||Molecular Weight|
Min / Max
|Non-lineage Restricted Molecule|
Type 1 glycoprotein
|50 / 50|
60 / 60
|CD16a is expressed on the transmembrane form in humans on NK cells, macrophages, activated monocytes, mast cells and γ/δ T cells. In the mouse, no GPI-anchored form of CD16a has been identified and the transmembrane form is expressed on macrophages, NK cells, neutrophils, myeloid precursors and on the majority of early CD4-CD8-TCR- fetal thymocytes.|
|MOLECULAR FAMILY NAME: Belongs to the immunoglobulin supergene family.|
CD16a is single-pass type-1 glycoprotein. It contains an extracellular domain which contains 2 Ig-like C2-type domains, a transmembrane and a cytoplasmic domain.
POST-TRANSCRIPTIONAL MODIFICATION: No information.
POST-TRANSLATIONAL MODIFICATION: No information.
|LIGANDS AND MOLECULES ASSOCIATED WITH CD16a|
The transmembrane form is non-covalently associated with the FceRI g chain or the TCR z chain. CD16a on mast cells is also associated with the b chain of the FceRI.
|CD16a is a low affinity receptor for aggregated IgG2 and IgG3. The transmembrane form binds IgG complexed to antigens and mediates phagocytosis and antibody-dependent cellular cytotoxicity (ADCC). Triggering in NK cells leads to ADDC and lymphokine production, indicating a role in defense against viral infection and neoplasms. On NK cells, signal transduction by CD16a is mediated through the g chain and crosslinking of CD16a with immune complexes or CD16a-specific mAbs induces calcium mobilization and hydrolysis of membrane phosphoinositides. In contrast, the GPI-anchored form (CD16b) on neutrophils binds to ligands but is unable to induce any signal or functional effect. CD16a associates with FcεRγ-chain on human phagocytes and mast cells and the TCR-ζ-chain in NK cells. Targeted disruption of the mouse FcRg chain common to CD16a and FceRI results in immunocompromised mice.|
BIOCHEMICAL ACTIVITY: No information.
DISEASE RELEVANCE AND FUNCTION OF CD16a IN INTACT ANIMAL
CD16a is a phenotypic marker in leukemia and HIV-1 and is used to purify bone marrow and germinal center subsets. CD16a alleles (and CD32) can be used as risk markers for systemic lupus erythematosus (SLE). CD16a-dependent but antibody-independent lysis of tumor cells and virus infected cell has been demonstrated.
|CD16a (FcgRIIIa) has a structural similarity to CD64 (FcgRI), CD32 (FcgRII) and CD64 (FcgRIa). The sequence LFAVDTGL is completely conserved in the transmembrane regions of CD16a and FcgRIa from human, mouse and rat. A family of CD16a isoforms have been described in the rat. |
PROTEIN AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD16a: No information.
SUBSTRATES: No information.
ENZYMES WHICH MODIFY CD16a: No information.
Database accession numbers
Revised June 25, 2008