P01872
uniprot
P01872
canonical
amino_acid_sequence
SQSFPNVFPLVSCESPLSDKNLVAMGCLARDFLPSTISFTWNYQNNTEVIQGIRTFPTLRTGGKYLATSQVLLSPKSILEGSDEYLVCKIHYGGKNRDLHVPIPAVAEMNPNVNVFVPPRDGFSGPAPRKSKLICEATNFTPKPITVSWLKDGKLVESGFTTDPVTIENKGSTPQTYKVISTLTISEIDWLNLNVYTCRVDHRGLTFLKNVSSTCAASPSTDILTFTIPPSFADIFLSKSANLTCLVSNLATYETLNISWASQSGEPLETKIKIMESHPNGTFSAKGVASVCVEDWNNRKEFVCTVTHRDLPSPQKKFISKPNEVHKHPPAVYLLPPAREQLNLRESATVTCLVKGFSPADISVQWLQRGQLLPQEKYVTSAPMPEPGAPGFYFTHSILTVTEEEWNSGETYTCVVGHEALPHLVTERTVDKSTGKPTLYNVSLIMSDTGGTCY
uniprot
proteins
function
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 (By similarity). 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 (By similarity). {ECO:0000250|UniProtKB:P01871}.; FUNCTION: [Isoform 1]: Constant region of secreted IgM (sIgM), also known as the Fc region of IgM antibody. Able to multimerize, forms high order polymers, mainly pentamers and occasionally hexamers, providing for multivalency and high avidity recognition of antigens (By similarity). Natural sIgM are polyreactive and recognize conserved self- and pathogen-derived structures, whereas immune sIgM are secreted only upon exposure to pathogens and are antigen-specific. Both natural and immune sIgM are required for an efficient humoral immune response to infection (PubMed:10899913, PubMed:28135254, PubMed:34788614). Mediates sIgM effector functions mostly via Fc receptors and the complement system. On lymphoid cells binds high-affinity Fc receptor FCMR and promotes induction of an efficient neutralizing IgG response while maintaining tolerance to self-antigens. Recruits C1q complement component to initiate the classical complement pathway, facilitating the recognition and neutralization of pathogens by the host. Together with C1q and mannose-binding lectin promotes the phagocytosis of apoptotic cells by macrophages, ensuring the clearance of potential autoimmune epitopes from tissues (By similarity) (PubMed:10899913, PubMed:11062505, PubMed:28135254). Involved in mucosal immunity. It is transported by transcytosis across mucosal epithelium by PIGR and secreted on the apical side in complex with PIGR secretory component to scan mucosal lining for pathogens. IgM-antigen complexes undergo FCMR-mediated retrotranscytosis across mucosal M cells toward antigen-presenting cells in mucosal lymphoid tissues (PubMed:34788614). {ECO:0000250|UniProtKB:P01871, ECO:0000269|PubMed:10899913, ECO:0000269|PubMed:11062505, ECO:0000269|PubMed:28135254, ECO:0000269|PubMed:34788614}.; FUNCTION: [Isoform 2]: Constant region of membrane-bound IgM, part of the B cell receptor complex (BCR). IgM BCR provides constitutive tonic signaling for B cell survival. Mediates pre-BCR signaling that regulates B cell selection and rearrangement of Ig genes via allelic exclusion. {ECO:0000269|PubMed:1545868, ECO:0000269|PubMed:1901381, ECO:0000269|PubMed:28135254}.
uniprot
proteins
mass_dalton
49972
uniprot
proteins
mutagenesis
MUTAGEN 96; /note="N->A: Abolishes formation of 55 kDa cleavage product."; /evidence="ECO:0000269|PubMed:29323348"; MUTAGEN 215; /note="C->S: Impairs dimerization."; /evidence="ECO:0000269|PubMed:23733956"; MUTAGEN 292; /note="C->S: Impairs dimerization."; /evidence="ECO:0000269|PubMed:23733956"; MUTAGEN 414; /note="C->S: Abolishes interaction with CD5L."; /evidence="ECO:0000269|PubMed:30324136"; MUTAGEN 453; /note="C->S: Impairs dimerization and oligomerization."; /evidence="ECO:0000269|PubMed:23733956
uniprot
proteins
post_translational_modification
PTM: Cleaved by a non-enzymatic process after Asn-96, yielding a glycosylated protein of 55 kDa. The process is induced by other proteins, and requires neutral or alkaline pH. {ECO:0000269|PubMed:29323348}.; PTM: N-glycosylated; important for IgM secretion and its localization at the plasma membrane. The interaction with FCMR is glycan-independent. {ECO:0000250|UniProtKB:P01871}.
uniprot
proteins
pubmed
10899913
uniprot
proteins
pubmed
11062505
uniprot
proteins
pubmed
111247
uniprot
proteins
pubmed
12654314
uniprot
proteins
pubmed
1545868
uniprot
proteins
pubmed
1901381
uniprot
proteins
pubmed
21183079
uniprot
proteins
pubmed
23733956
uniprot
proteins
pubmed
2415657
uniprot
proteins
pubmed
28135254
uniprot
proteins
pubmed
29323348
uniprot
proteins
pubmed
30324136
uniprot
proteins
pubmed
34788614
uniprot
proteins
pubmed
6255422
uniprot
proteins
pubmed
6260591
uniprot
proteins
pubmed
6771019
uniprot
proteins
pubmed
6771020
uniprot
proteins
pubmed
6795090
uniprot
proteins
pubmed
6816276
uniprot
proteins
sequence_length
454
uniprot
proteins
subcellular_location
SUBCELLULAR LOCATION: [Isoform 1]: Secreted {ECO:0000269|PubMed:10899913, ECO:0000269|PubMed:11062505}. Note=During differentiation, B-lymphocytes switch from expression of membrane-bound IgM to secretion of IgM.; SUBCELLULAR LOCATION: [Isoform 2]: Cell membrane {ECO:0000269|PubMed:10899913}; Single-pass membrane protein {ECO:0000255}.
uniprot
proteins