Tapasin

TAP binding protein (tapasin)
Available structures PDB Ortholog search: PDBe, RCSB List of PDB id codes 3F8U​
Identifiers
Symbols	TAPBP ; NGS17; TAPA; TPN; TPSN
External IDs	OMIM: 601962 MGI: 1201689 HomoloGene: 2401 GeneCards: TAPBP Gene
Gene ontology Molecular function • protein binding • peptide antigen-transporting ATPase activity • MHC class I protein binding • peptide antigen binding • TAP1 binding • TAP2 binding • unfolded protein binding Cellular component • Golgi membrane • endoplasmic reticulum • endoplasmic reticulum membrane • integral component of membrane • MHC class I peptide loading complex • TAP complex • integral component of lumenal side of endoplasmic reticulum membrane Biological process • antigen processing and presentation of peptide antigen via MHC class I • antigen processing and presentation of exogenous peptide antigen via MHC class I, TAP-dependent • protein complex assembly • retrograde vesicle-mediated transport, Golgi to ER • immune response • peptide transport • antigen processing and presentation of endogenous peptide antigen via MHC class I • antigen processing and presentation of exogenous peptide antigen via MHC class I • amide transport • peptide antigen stabilization Sources: Amigo / QuickGO
RNA expression pattern
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: 33.3 – 33.31 Mb	Chr 17: 33.92 – 33.93 Mb
PubMed search

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

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

Tapasin has been shown to interact with:

• HLA-A,^[5] and
• TAP1^[5][6]

See also

• Transporter associated with antigen processing ("TAP")

References

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. "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. 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". J. Biol. Chem. 277 (21): 18266–71. doi:10.1074/jbc.M201388200. PMID 11884415.
6. Raghuraman G, Lapinski PE, Raghavan M (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. 277 (44): 41786–94. doi:10.1074/jbc.M207128200. PMID 12213826.

Further reading

• Schneeweiss C, Garstka M, Smith J, Hütt MT, Springer S (2009). "The mechanism of action of tapasin in the peptide exchange on MHC class I molecules determined from kinetics simulation studies". Mol. Immunol. 46 (10): 2054–2063. doi:10.1016/j.molimm.2009.02.032. PMID 19362740.
• Turnquist HR, Vargas SE, Schenk EL, McIlhaney MM, Reber AJ, Solheim JC (2002). "The interface between tapasin and MHC class I: identification of amino acid residues in both proteins that influence their interaction". Immunol. Res. 25 (3): 261–9. doi:10.1385/IR:25:3:261. PMID 12018464.
• Momburg F, Tan P (2002). "Tapasin-the keystone of the loading complex optimizing peptide binding by MHC class I molecules in the endoplasmic reticulum". Mol. Immunol. 39 (3–4): 217–33. doi:10.1016/S0161-5890(02)00103-7. PMID 12200052.
• Dissemond J, Kothen T, Mörs J, Weimann TK, Lindeke A, Goos M, Wagner SN (2004). "Downregulation of tapasin expression in progressive human malignant melanoma". Arch. Dermatol. Res. 295 (2): 43–9. doi:10.1007/s00403-003-0393-8. PMID 12682852.
• Paulsson K, Wang P (2003). "Chaperones and folding of MHC class I molecules in the endoplasmic reticulum". Biochim. Biophys. Acta 1641 (1): 1–12. doi:10.1016/S0167-4889(03)00048-X. PMID 12788224.
• Andersson B, Wentland MA, Ricafrente JY, Liu W, Gibbs RA (1996). "A "double adaptor" method for improved shotgun library construction". Anal. Biochem. 236 (1): 107–13. doi:10.1006/abio.1996.0138. PMID 8619474.
• Sadasivan B, Lehner PJ, Ortmann B, Spies T, Cresswell P (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.
• Lewis JW, Neisig A, Neefjes J, Elliott T (1997). "Point mutations in the alpha 2 domain of HLA-A2.1 define a functionally relevant interaction with TAP". Curr. Biol. 6 (7): 873–83. doi:10.1016/S0960-9822(02)00611-5. PMID 8805302.
• Yu W, Andersson B, Worley KC, Muzny DM, Ding Y, Liu W, Ricafrente JY, Wentland MA, Lennon G, Gibbs RA (1997). "Large-scale concatenation cDNA sequencing". Genome Res. 7 (4): 353–8. doi:10.1101/gr.7.4.353. PMC 139146. PMID 9110174.
• Li S, Sjögren HO, Hellman U, Pettersson RF, Wang P (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.
• Ortmann B, Copeman J, Lehner PJ, Sadasivan B, Herberg JA, Grandea AG, Riddell SR, Tampé R, Spies T, Trowsdale J, Cresswell P (1997). "A critical role for tapasin in the assembly and function of multimeric MHC class I-TAP complexes". Science 277 (5330): 1306–9. doi:10.1126/science.277.5330.1306. PMID 9271576.
• Herberg JA, Sgouros J, Jones T, Copeman J, Humphray SJ, Sheer D, Cresswell P, Beck S, Trowsdale J (1998). "Genomic analysis of the Tapasin gene, located close to the TAP loci in the MHC". Eur. J. Immunol. 28 (2): 459–67. doi:10.1002/(SICI)1521-4141(199802)28:02<459::AID-IMMU459>3.0.CO;2-Z. PMID 9521053.
• Lindquist JA, Jensen ON, Mann M, Hämmerling GJ (1998). "ER-60, a chaperone with thiol-dependent reductase activity involved in MHC class I assembly". EMBO J. 17 (8): 2186–95. doi:10.1093/emboj/17.8.2186. PMC 1170563. PMID 9545232.
• Herberg JA, Beck S, Trowsdale J (1998). "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. 277 (4): 839–57. doi:10.1006/jmbi.1998.1637. PMID 9545376.
• Furukawa H, Kashiwase K, Yabe T, Ishikawa Y, Akaza T, Tadokoro K, Tohma S, Inoue T, Tokunaga K, Yamamoto K, Juji T (1999). "Polymorphism of TAPASIN and its linkage disequilibria with HLA class II genes in the Japanese population". Tissue Antigens 52 (3): 279–81. doi:10.1111/j.1399-0039.1998.tb03044.x. PMID 9802609.
• El Ouakfaoui S, Heitz D, Paquin R, Beaulieu AD (1999). "Granulocyte-macrophage colony-stimulating factor modulates tapasin expression in human neutrophils". J. Leukoc. Biol. 65 (2): 205–10. PMID 10088603.
• Bangia N, Lehner PJ, Hughes EA, Surman M, Cresswell P (1999). "The N-terminal region of tapasin is required to stabilize the MHC class I loading complex". Eur. J. Immunol. 29 (6): 1858–70. doi:10.1002/(SICI)1521-4141(199906)29:06<1858::AID-IMMU1858>3.0.CO;2-C. PMID 10382748.
• Knittler MR, Alberts P, Deverson EV, Howard JC (2000). "Nucleotide binding by TAP mediates association with peptide and release of assembled MHC class I molecules". Curr. Biol. 9 (18): 999–1008. doi:10.1016/S0960-9822(99)80448-5. PMID 10508608.
• Li S, Paulsson KM, Chen S, Sjögren HO, Wang P (2000). "Tapasin is required for efficient peptide binding to transporter associated with antigen processing". J. Biol. Chem. 275 (3): 1581–6. doi:10.1074/jbc.275.3.1581. PMID 10636848.
• Tan P, Kropshofer H, Mandelboim O, Bulbuc N, Hämmerling GJ, Momburg F (2002). "Recruitment of MHC class I molecules by tapasin into the transporter associated with antigen processing-associated complex is essential for optimal peptide loading". J. Immunol. 168 (4): 1950–60. doi:10.4049/jimmunol.168.4.1950. PMID 11823531.
• Mayer WE, Klein J (2002). "Is tapasin a modified Mhc class I molecule?". Immunogenetics 53 (9): 719–23. doi:10.1007/s00251-001-0403-y. PMID 11862402.

External links

• tapasin at the US National Library of Medicine Medical Subject Headings (MeSH)