IGHG3

Function

Constant region of immunoglobulin heavy chains. Immunoglobulins, also known as antibodies, are membrane-bound or secreted glycoproteins produced by B lymphocytes. In the recognition phase of humoral immunity, the membrane-bound immunoglobulins serve as receptors which, upon binding of a specific antigen, trigger the clonal expansion and differentiation of B lymphocytes into immunoglobulins-secreting plasma cells. Secreted immunoglobulins mediate the effector phase of humoral immunity, which results in the elimination of bound antigens (PubMed:20176268, PubMed:22158414). The antigen binding site is formed by the variable domain of one heavy chain, together with that of its associated light chain. Thus, each immunoglobulin has two antigen binding sites with remarkable affinity for a particular antigen. The variable domains are assembled by a process called V-(D)-J rearrangement and can then be subjected to somatic hypermutations which, after exposure to antigen and selection, allow affinity maturation for a particular antigen (PubMed:17576170, PubMed:20176268).

Post-translational modifications

N-linked glycans at Asn-322 are noncore fucosylated and the vast majority are diantennary species with a bisecting GlcNAc. Among them the most dominant glycans are HexNAc5Hex4, HexNAc5Hex5, and HexNAc5Hex5Sia1.

N-linked glycans at Asn-227 are diantennary core fucosylated structures without bisecting GlcNAc (HexNAc4Hex4Fuc1, HexNAc4Hex5Fuc1, and HexNAc4Hex5Fuc1Sia1) (PubMed:26536155). Glycosylation on Asn-227 is required for interaction with Fc receptors and ability to activate the complement pathway (PubMed:20357243).

(Microbial infection) Deglycosylation on Asn-227 by S.pyogenes EndoS or Endos2 endoglucosidases prevents interaction between immunoglobulin-gamma (IgG) and Fc receptors, impairing ability to activate the complement pathway.

O-linked glycans are non-, mono- and disialylated core 1-type O-glycans.

Cellular localization

• Isoform 1
• Secreted
• Isoform 2
• Cell membrane
• Single-pass membrane protein

Alternative names

Immunoglobulin heavy constant gamma 3, HDC, Heavy chain disease protein, Ig gamma-3 chain C region, IGHG3

Database links

swissprot:P01860 swissprot:P01861 swissprot:P01857 swissprot:P01859 entrezGene:3500 entrezGene:3503 omim:147110 omim:147120 omim:147130 entrezGene:3501 entrezGene:3502 omim:147100