Recombinant Human Tapasin (TAPBP), partial

Function

Involved in the association of MHC class I with transporter associated with antigen processing (TAP) and in the assembly of MHC class I with peptide (peptide loading)

Subcellular Location

Endoplasmic reticulum membrane (Single-pass type I membrane protein)

Disease Association

MHC class I deficiency 3 (MHC1D3) : An autosomal recessive disorder characterized by glomerulonephritis and markedly reduced cell surface expression of class I HLA antigens. Additional features are herpes zoster infection and polyps of the stomach and colon. [The disease is caused by variants affecting the gene represented in this entry]

Tissue Specificity

Neutrophils, mostly in fully differentiated cells

Subunit

Heterodimer with PDIA3; disulfide-linked. Obligatory mediator for the interaction between newly assembled MHC class I molecules, calreticulin, PDIA3 and TAP. Up to 4 MHC class I/tapasin complexes bind to 1 TAP (PubMed:19119025, PubMed:21263072, PubMed:26611325). Interacts with HLA-G-B2M complex; this interaction is required for loading of high affinity peptides (PubMed:21263072). On its own or as part of MHC class I peptide loading complex, interacts with ligand-free MR1 or MR1-B2M complex, providing for stable MR1 pools ready for metabolite antigen processing (PubMed:32958637)

• Li S. et al. Cloning and functional characterization of a subunit of the transporter associated with antigen processing. — Proc. Natl. Acad. Sci. U.S.A. (1997)
• Ortmann B. et al. A critical role for tapasin in the assembly and function of multimeric MHC class I-TAP complexes. — Science (1997)
• Herberg J.A. et al. Genomic analysis of the Tapasin gene, located close to the TAP loci in the MHC. — Eur. J. Immunol. (1998)
• Herberg J.A. et al. TAPASIN, DAXX, RGL2, HKE2 and four new genes (BING 1, 3 to 5) form a dense cluster at the centromeric end of the MHC. — J. Mol. Biol. (1998)
• Furukawa H. et al. Polymorphism of TAPASIN and its linkage disequilibria with HLA class II genes in the Japanese population. — Tissue Antigens (1998)
• El Ouakfaoui S. et al. Granulocyte-macrophage colony-stimulating factor modulates tapasin expression in human neutrophils. — J. Leukoc. Biol. (1999)
• Gao B. et al. Generation of a functional, soluble tapasin protein from an alternatively spliced mRNA. — Genes Immun. (2004)
• Belicha-Villanueva A. et al. Identification of an alternate splice form of tapasin in human melanoma. — Hum. Immunol. (2010)