IGHA1

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). Ig alpha is the major immunoglobulin class in body secretions (PubMed:2241915).

Involvement in disease

A chromosomal aberration involving IGHA1 is found in multiple myeloma (MM) cell lines. Translocation t(1;14)(q21;q32) that forms a FCRL4-IGHA1 fusion protein.

Post-translational modifications

Isoform 1

3-Hydroxykynurenine, an oxidized tryptophan metabolite that is common in biological fluids, reacts with alpha-1-microglobulin to form heterogeneous polycyclic chromophores including hydroxanthommatin. The chromophore reacts with accessible cysteines forming non-reducible thioether cross-links with Ig alpha-1 chain C region Cys-352.

N- and O-glycosylated. N-glycan at Asn-144: Hex5HexNAc4.

Cellular localization

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

Alternative names

Immunoglobulin heavy constant alpha 1, Ig alpha-1 chain C region, Ig alpha-1 chain C region BUR, Ig alpha-1 chain C region TRO, IGHA1

Database links

swissprot:P01876 entrezGene:3494 entrezGene:3493 omim:146900 omim:147000 omim:173880 swissprot:P01877 entrezGene:5284