Search by BoMiProt ID - Bomi331

Primary Information

BoMiProt ID Bomi331
Protein Name Immunoglobulin J chain
Organism Bos taurus
Uniprot IDQ3SYR8
Milk FractionWhey, MFGM, Exosome
Ref Sequence ID NP_786967.1
Aminoacid Length 157
Molecular Weight 17857
FASTA Sequence Download
Gene Name JCHAIN
Gene ID 280821
Protein Existence Status Unreviewed: Experimental evidence at protein level

Secondary Information

Presence in other biological fluids/tissue/cells expressed by mucosal and glandular plasma cells; bone marrow, spleen and lymph nodes
Endogenous/Bioactive peptides - Fragment - Sequence - Effect IgG, IgA - Immunomodulatory (Passive immunity) Ref
Protein Function joining (J) chain is a small polypeptide; regulates polymer formation of immunoglobulin (Ig)A and IgM; endows antibodies with high valency of antigen-binding sites, which makes them suitable for agglutinating bacteria and viruses; mediates active external transfer of pIgA and pentameric IgM to exocrine secretions; involved in creating the binding site for polymericIg receptor (pIgR) and secretory component (SC) in the Ig polymers; both the J chain and pIgR/SC are key proteins in secretory immunity; may be a marker for relatively `early' B-cell clones derived from mucosa-associated lymphoid tissue
Biochemical Properties only J-chain-containing polymers show high affnity for the polymeric Ig receptor; J-chain-negative hexameric IgM is at least 15±20-fold more effecient than J-chain-positive pentameric IgM in activating complement; Characterization of J chain released from dimeric, trimeric and tetrameric IgA puriied from the same myeloma serum suggested that the molar J-chain ratio increases with the size of the polymer
Significance in milk provide protection against enteric and other diseases in infants; The primary immunoglobulin in cow colostrum and milk is IgG, whereas the primary immunoglobulin in human milk is IgA; provide passive immunity to protect animals
PTMs glycoprotein; N linked glycosylation at 39th aa in both bovine and humans; contains eight cysteine residues: two (cys15 and cys69) are involved in disulfide bridges with the α or µ chains; and six are involved in intrachain disulfide bridges
Site(s) of PTM(s)

N-glycosylation, O-glycosylation,
Bibliography 1. Max, E. E. and Korsmeyer, S. J. (1985) ‘Human J chain gene. Structure and expression in B lymphoid cells’, Journal of Experimental Medicine, 161(4), pp. 832–849. doi: 10.1084/jem.161.4.832.
2. Wiersma, E. J. et al. (1998) ‘Structural and functional analysis of J chain-deficient IgM.’, Journal of immunology (Baltimore, Md. : 1950), 160(12), pp. 5979–89. Available at: (Accessed: 3 October 2019).