UniProt functional annotation for O15533



	UniProt functional annotation for O15533

UniProt code: O15533.

Organism: Homo sapiens (Human).

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

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). {ECO:0000269|PubMed:10636848, ECO:0000269|PubMed:12582157, ECO:0000269|PubMed:21263072, ECO:0000269|PubMed:26611325}.

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. {ECO:0000269|PubMed:12582157, ECO:0000269|PubMed:19119025, ECO:0000269|PubMed:21263072}.

Subcellular location: Endoplasmic reticulum membrane {ECO:0000305}; Single-pass type I membrane protein {ECO:0000305}.

Tissue specificity: Neutrophils, mostly in fully differentiated cells.

Domain: The N-terminus is required for efficient association with MHC class I molecule and for a stable interaction between MHC I and calreticulin. Binding to TAP is mediated by the C-terminal region. {ECO:0000269|PubMed:10382748}.

Polymorphism: The 2 alleles of TAPBP; TAPBP*01 (Tapasin*01) (shown here) and TAPBP*02 (Tapasin*02); are in linkage disequilibria with the HLA-DRB1 locus in a Japanese population. {ECO:0000269|PubMed:9802609}.

Disease: Bare lymphocyte syndrome 1 (BLS1) [MIM:604571]: A HLA class I deficiency. Contrary to bare lymphocyte syndromes type 2 and type 3, which are characterized by early-onset severe combined immunodeficiency, class I antigen deficiencies are not accompanied by particular pathologic manifestations during the first years of life. Systemic infections have not been described. Chronic bacterial infections, often beginning in the first decade of life, are restricted to the respiratory tract. {ECO:0000269|PubMed:12149238}. Note=The disease is caused by variants affecting the gene represented in this entry.

Miscellaneous: [Isoform 2]: Due to a partial intron retention. {ECO:0000305}.

Sequence caution: Sequence=AAD32924.2; Type=Miscellaneous discrepancy; Note=Probable cloning artifact.; 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:		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). {ECO:0000269\|PubMed:10636848, ECO:0000269\|PubMed:12582157, ECO:0000269\|PubMed:21263072, ECO:0000269\|PubMed:26611325}.


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. {ECO:0000269\|PubMed:12582157, ECO:0000269\|PubMed:19119025, ECO:0000269\|PubMed:21263072}.
Subcellular location:		Endoplasmic reticulum membrane {ECO:0000305}; Single-pass type I membrane protein {ECO:0000305}.
Tissue specificity:		Neutrophils, mostly in fully differentiated cells.
Domain:		The N-terminus is required for efficient association with MHC class I molecule and for a stable interaction between MHC I and calreticulin. Binding to TAP is mediated by the C-terminal region. {ECO:0000269\|PubMed:10382748}.
Polymorphism:		The 2 alleles of TAPBP; TAPBP01 (Tapasin01) (shown here) and TAPBP02 (Tapasin02); are in linkage disequilibria with the HLA-DRB1 locus in a Japanese population. {ECO:0000269\|PubMed:9802609}.
Disease:		Bare lymphocyte syndrome 1 (BLS1) [MIM:604571]: A HLA class I deficiency. Contrary to bare lymphocyte syndromes type 2 and type 3, which are characterized by early-onset severe combined immunodeficiency, class I antigen deficiencies are not accompanied by particular pathologic manifestations during the first years of life. Systemic infections have not been described. Chronic bacterial infections, often beginning in the first decade of life, are restricted to the respiratory tract. {ECO:0000269\|PubMed:12149238}. Note=The disease is caused by variants affecting the gene represented in this entry.
Miscellaneous:		[Isoform 2]: Due to a partial intron retention. {ECO:0000305}.
Sequence caution:		Sequence=AAD32924.2; Type=Miscellaneous discrepancy; Note=Probable cloning artifact.; Evidence={ECO:0000305};