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Available structures
PDBOrtholog search: PDBe RCSB
AliasesTAPBP, NGS17, TAPA, TPN, TPSN, TAP binding protein (tapasin), TAP binding protein
External IDsOMIM: 601962 MGI: 1201689 HomoloGene: 2401 GeneCards: TAPBP
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC)Chr 6: 33.3 – 33.31 MbChr 17: 34.13 – 34.15 Mb
PubMed search[3][4]
View/Edit HumanView/Edit Mouse

TAP-associated glycoprotein, also known as tapasin or TAPBP, is a protein[5][6] that in humans is encoded by the TAPBP gene.[7]


The TAPBP gene encodes a transmembrane glycoprotein that mediates interaction between newly assembled major histocompatibility complex (MHC) class I molecules and the transporter associated with antigen processing (TAP), which is required for the transport of antigenic peptides across the endoplasmic reticulum membrane. This interaction facilitates optimal peptide loading on the MHC class I molecule. Up to four complexes of MHC class I and tapasin may be bound to a single TAP molecule. Tapasin contains a C-terminal double-lysine motif (KKKAE) known to maintain membrane proteins in the endoplasmic reticulum. In humans, the tapasin gene lies within the major histocompatibility complex on chromosome 6. Alternative splicing results in three transcript variants encoding different isoforms.[7]

Tapasin is a MHC class I antigen-processing molecule present in the lumen of the endoplasmic reticulum. It plays an important role in the maturation of MHC class I molecules in the ER lumen. Tapasin is one component of the peptide-loading complex, and can be found associated with MHC class I molecules after the MHC class I heavy chain has associated with Beta2 microglobulin. The peptide-loading complex consists of TAP, tapasin, MHC class I, calreticulin, and ERp57. Tapasin recruits MHC class I molecules to the TAP peptide transporter, and also enhances loading of MHC class I with high-affinity peptides. Following loading of MHC class I with a high-affinity ligand, the interaction between tapasin and MHC class I disappears.[8]


Tapasin has been shown to interact with:

See also[edit]


  1. ^ a b c ENSG00000236490, ENSG00000206281, ENSG00000206208, ENSG00000112493 GRCh38: Ensembl release 89: ENSG00000231925, ENSG00000236490, ENSG00000206281, ENSG00000206208, ENSG00000112493 - Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000024308 - Ensembl, May 2017
  3. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. ^ Sadasivan B, Lehner PJ, Ortmann B, Spies T, Cresswell P (August 1996). "Roles for calreticulin and a novel glycoprotein, tapasin, in the interaction of MHC class I molecules with TAP". Immunity. 5 (2): 103–14. doi:10.1016/S1074-7613(00)80487-2. PMID 8769474.
  6. ^ Li S, Sjögren HO, Hellman U, Pettersson RF, Wang P (August 1997). "Cloning and functional characterization of a subunit of the transporter associated with antigen processing". Proceedings of the National Academy of Sciences of the United States of America. 94 (16): 8708–13. Bibcode:1997PNAS...94.8708L. doi:10.1073/pnas.94.16.8708. PMC 23091. PMID 9238042.
  7. ^ a b "Entrez Gene: TAPBP TAP binding protein (tapasin)".
  8. ^ Zhang Y, Williams DB (2006). "Assembly of MHC class I molecules within the endoplasmic reticulum". Immunologic Research. 35 (1–2): 151–62. doi:10.1385/IR:35:1:151. PMID 17003517. S2CID 27816994.
  9. ^ a b Paulsson KM, Kleijmeer MJ, Griffith J, Jevon M, Chen S, Anderson PO, Sjogren HO, Li S, Wang P (May 2002). "Association of tapasin and COPI provides a mechanism for the retrograde transport of major histocompatibility complex (MHC) class I molecules from the Golgi complex to the endoplasmic reticulum". The Journal of Biological Chemistry. 277 (21): 18266–71. doi:10.1074/jbc.M201388200. PMID 11884415.
  10. ^ Raghuraman G, Lapinski PE, Raghavan M (November 2002). "Tapasin interacts with the membrane-spanning domains of both TAP subunits and enhances the structural stability of TAP1 x TAP2 Complexes". The Journal of Biological Chemistry. 277 (44): 41786–94. doi:10.1074/jbc.M207128200. PMID 12213826.

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