Tapasin

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TAP binding protein (tapasin)
Available structures
PDB Ortholog search: PDBe, RCSB
Identifiers
Symbols TAPBP ; NGS17; TAPA; TPN; TPSN
External IDs OMIM601962 MGI1201689 HomoloGene2401 GeneCards: TAPBP Gene
RNA expression pattern
PBB GE TAPBP 210294 at tn.png
PBB GE TAPBP 208829 at tn.png
More reference expression data
Orthologs
Species Human Mouse
Entrez 6892 21356
Ensembl ENSG00000112493 ENSMUSG00000024308
UniProt O15533 Q9R233
RefSeq (mRNA) NM_003190 NM_001025313
RefSeq (protein) NP_003181 NP_001020484
Location (UCSC) Chr 6:
33.27 – 33.28 Mb
Chr 17:
33.92 – 33.93 Mb
PubMed search [1] [2]

TAP-associated glycoprotein also known as tapasin or TAPBP is a protein[1][2] that in humans is encoded by the TAPBP gene.[3]

Function[edit]

This 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.[3]

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.[4]

Interactions[edit]

Tapasin has been shown to interact with TAP1[5][6] and HLA-A.[6]

See also[edit]

References[edit]

  1. ^ 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. 
  2. ^ 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". Proc. Natl. Acad. Sci. U.S.A. 94 (16): 8708–13. doi:10.1073/pnas.94.16.8708. PMC 23091. PMID 9238042. 
  3. ^ a b "Entrez Gene: TAPBP TAP binding protein (tapasin)". 
  4. ^ Zhang Y, Williams DB (2006). "Assembly of MHC class I molecules within the endoplasmic reticulum". Immunol. Res. 35 (1–2): 151–62. doi:10.1385/IR:35:1:151. PMID 17003517. 
  5. ^ Raghuraman, Gayatri; Lapinski Philip Edward, Raghavan Malini (Nov 2002). "Tapasin interacts with the membrane-spanning domains of both TAP subunits and enhances the structural stability of TAP1 x TAP2 Complexes". J. Biol. Chem. (United States) 277 (44): 41786–94. doi:10.1074/jbc.M207128200. ISSN 0021-9258. PMID 12213826. 
  6. ^ a b Paulsson, Kajsa M; Kleijmeer Monique J, Griffith Janice, Jevon Marc, Chen Shangwu, Anderson Per O, Sjogren Hans-Olov, Li Suling, Wang Ping (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". J. Biol. Chem. (United States) 277 (21): 18266–71. doi:10.1074/jbc.M201388200. ISSN 0021-9258. PMID 11884415. 

Further reading[edit]

External links[edit]