TAPBP
TAP Binding Protein (Tapasin) – Key Regulator of MHC Class I Antigen Presentation
Gene Information Card
| Symbol | TAPBP |
|---|---|
| Full Name | TAP binding protein (tapasin) |
| Gene Type | protein-coding |
| Chromosomal Location | 6p21.32 |
| NCBI Gene ID | 6892 ncbi.nlm.nih.gov/gene/6892 |
| Ensembl ID | ENSG00000231925 |
| UniProt ID | O15533 |
| OMIM ID | 601962 |
| HGNC ID | 11566 |
| Aliases | TPSN, TAPBP-R, TAPBP-S, tapasin |
Description
TAPBP encodes tapasin, a transmembrane glycoprotein that bridges the transporter associated with antigen processing (TAP) and MHC class I molecules. Tapasin stabilizes the peptide-loading complex, facilitates peptide editing, and ensures optimal MHC class I antigen presentation to CD8+ T cells. It is critical for immune surveillance and adaptive immunity.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Bare lymphocyte syndrome type I (BLS I) | Loss-of-function mutations in TAPBP impair MHC class I surface expression, leading to deficient CD8+ T-cell responses. | OMIM #604571; ClinVar |
| Autoimmune diseases (e.g., type 1 diabetes, rheumatoid arthritis) | Polymorphisms in TAPBP may alter peptide loading and influence autoantigen presentation. | GWAS; NCBI |
| Cancer (e.g., cervical, lung, colorectal) | Reduced tapasin expression correlates with immune evasion and poor prognosis. | COSMIC; literature review |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Lymph node | 48.2 | High |
| Spleen | 42.1 | High |
| Lung | 18.5 | Medium |
| Small intestine | 15.3 | Medium |
| Liver | 4.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa (cervical carcinoma) | 35.6 | High expression |
| A549 (lung carcinoma) | 22.1 | Medium expression |
| HepG2 (hepatocellular carcinoma) | 5.8 | Low expression |
| Jurkat (T-cell leukemia) | 50.3 | Very high expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1072C>T (p.Arg358*) | Nonsense | Rare | Loss of function; truncated protein |
| c.1A>G (p.Met1?) | Start loss | Very rare | No protein production |
| c.793G>A (p.Gly265Arg) | Missense | Rare | Impaired TAP binding |
| c.1210_1211delAG (p.Ser404fs) | Frameshift | Rare | Premature stop; loss of function |
Mutation functional classification
Loss of Function (LOF)
Nonsense, frameshift, and start-loss mutations abolish tapasin expression or function, causing bare lymphocyte syndrome type I.
Gain of Function (GOF)
Not reported for TAPBP.
Dominant Negative (DN)
Not reported; TAPBP mutations are typically recessive.
View complete mutation data：
Gene Ontology (GO)
| • cellular response to DNA damage stimulus (GO:0006974) | • antigen processing and presentation of exogenous peptide antigen via MHC class I (GO:0002474) |
| • antigen processing and presentation of exogenous peptide antigen via MHC class I (GO:0002479) | • peptide antigen assembly with MHC class I protein complex (GO:0002501) |
| • protein binding (GO:0005515) | • plasma membrane (GO:0005886) |
| • integral component of membrane (GO:0016021) | • phagocytic vesicle membrane (GO:0030670) |
| • peptide antigen binding (GO:0042605) | • MHC class I protein complex (GO:0042612) |
Pathways
• Antigen processing and presentation (KEGG hsa04612)
• Endocytosis (KEGG hsa04144)
• Phagosome (KEGG hsa04145)
• Immune System (Reactome R-HSA-168256)
• MHC class I antigen presentation (Reactome R-HSA-983169)
Protein Summary
Tapasin (TAPBP) is a 48 kDa type I transmembrane protein with an N-terminal lumenal domain that binds MHC class I heavy chains, a transmembrane domain, and a short cytoplasmic tail. It forms a critical bridge between TAP and MHC class I, retaining empty MHC I molecules in the endoplasmic reticulum until high-affinity peptides are loaded. Tapasin also recruits ERp57 and calreticulin to the peptide-loading complex, ensuring proper peptide editing and quality control. Loss of tapasin leads to reduced MHC class I surface expression and impaired CD8+ T-cell activation.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| TAPBP Knockout HEK293 Cell Line | EDJ-KQ5884 | Human | 6892 | Details Get a Quote |
| TAPBPL Knockout HEK293 Cell Line | EDJ-KQ15611 | Human | 55080 | Details Get a Quote |
| TAPBP Knockout A-549 Cell Line | EDJ-KQ29378 | Human | 6892 | Details Get a Quote |
| TAPBP Knockout HCT 116 Cell Line | EDJ-KQ29379 | Human | 6892 | Details Get a Quote |
| TAPBP Knockout HeLa Cell Line | EDJ-KQ29380 | Human | 6892 | Details Get a Quote |
| TAPBPL Knockout A-549 Cell Line | EDJ-KQ46504 | Human | 55080 | Details Get a Quote |
| TAPBPL Knockout HeLa Cell Line | EDJ-KQ46505 | Human | 55080 | Details Get a Quote |
| TAPBPL Knockout HCT 116 Cell Line | EDJ-KQ73470 | Human | 55080 | Details Get a Quote |
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