UniProt functional annotation for P01876



	UniProt functional annotation for P01876

UniProt code: P01876.

Organism: Homo sapiens (Human).

Taxonomy: Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo.

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:22158414, PubMed:20176268). 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). {ECO:0000303|PubMed:17576170, ECO:0000303|PubMed:20176268, ECO:0000303|PubMed:22158414, ECO:0000303|PubMed:2241915}.

Subunit: Immunoglobulins are composed of two identical heavy chains and two identical light chains; disulfide-linked (PubMed:20176268). Monomeric or polymeric (PubMed:2241915). Part of the secretory IgA (sIgA) complex that consists of two, four or five IgA monomers, and two additional non-Ig polypeptides, namely the JCHAIN and the secretory component (the proteoytic product of PIGR). {ECO:0000269|PubMed:32029686, ECO:0000303|PubMed:20176268, ECO:0000303|PubMed:2241915}.

Subcellular location: Secreted {ECO:0000303|PubMed:20176268, ECO:0000303|PubMed:22158414}. Cell membrane {ECO:0000303|PubMed:20176268, ECO:0000303|PubMed:22158414}.

Ptm: 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. {ECO:0000269|PubMed:7506257}.

Ptm: N- and O-glycosylated. N-glycan at Asn-144: Hex5HexNAc4. {ECO:0000269|PubMed:15084671, ECO:0000269|PubMed:19139490, ECO:0000269|PubMed:19838169, ECO:0000269|PubMed:22171320}.

Polymorphism: There are several alleles. The sequence shown is that of IMGT allele IGHA1*02. {ECO:0000305}.

Disease: Note=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. {ECO:0000269|PubMed:11290337}.

Sequence caution: Sequence=AAC82528.1; Type=Erroneous initiation; Note=Truncated N-terminus.; Evidence={ECO:0000305};

Annotations taken from UniProtKB at the EBI.


Organism:		Homo sapiens (Human).
Taxonomy:		Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo.



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:22158414, PubMed:20176268). 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). {ECO:0000303\|PubMed:17576170, ECO:0000303\|PubMed:20176268, ECO:0000303\|PubMed:22158414, ECO:0000303\|PubMed:2241915}.


Subunit:		Immunoglobulins are composed of two identical heavy chains and two identical light chains; disulfide-linked (PubMed:20176268). Monomeric or polymeric (PubMed:2241915). Part of the secretory IgA (sIgA) complex that consists of two, four or five IgA monomers, and two additional non-Ig polypeptides, namely the JCHAIN and the secretory component (the proteoytic product of PIGR). {ECO:0000269\|PubMed:32029686, ECO:0000303\|PubMed:20176268, ECO:0000303\|PubMed:2241915}.
Subcellular location:		Secreted {ECO:0000303\|PubMed:20176268, ECO:0000303\|PubMed:22158414}. Cell membrane {ECO:0000303\|PubMed:20176268, ECO:0000303\|PubMed:22158414}.
Ptm:		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. {ECO:0000269\|PubMed:7506257}.
Ptm:		N- and O-glycosylated. N-glycan at Asn-144: Hex5HexNAc4. {ECO:0000269\|PubMed:15084671, ECO:0000269\|PubMed:19139490, ECO:0000269\|PubMed:19838169, ECO:0000269\|PubMed:22171320}.
Polymorphism:		There are several alleles. The sequence shown is that of IMGT allele IGHA1*02. {ECO:0000305}.
Disease:		Note=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. {ECO:0000269\|PubMed:11290337}.
Sequence caution:		Sequence=AAC82528.1; Type=Erroneous initiation; Note=Truncated N-terminus.; Evidence={ECO:0000305};