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antigen peptide transporter-2 (APT2), peptide transporter TAP2, peptide transporter PSF2, peptide supply factor 2 (PSF-2), RING11, Y1, PSF2, MTP-2 or HAM-2

Function: - pump which delivers peptides to class 1 MHC molecules within the endoplasmic reticulum of antigen presenting cells - role in the transport of antigens from the cytoplasm to the endoplasmic reticulum for association with MHC class 1 molecules - acts as a molecular scaffold for final stage of MHC class 1 folding, binding of peptide - nascent MHC class 1 molecules associate with TAP via tapasin - inhibited by covalent attachment of herpes simplex virus ICP47 protein, which blocks peptide-binding site of TAP - inhibited by human cytomegalovirus US6 glycoprotein, which binds to the lumenal side of the TAP complex & inhibits peptide translocation by specifically blocking ATP-binding to TAP1 & prevents the conformational rearrangement of TAP induced by peptide binding - inhibited by human adenovirus E3-19K glycoprotein, which binds the TAP complex & acts as a tapasin inhibitor, preventing MHC class 1/TAP association - heterodimer of TAP1 & TAP2 Structure: - peptide-binding site is shared between the cytoplasmic loops of TAP1 & TAP2 - belongs to the ABC transporter family, MHC peptide exporter (TC 3.A.1.209) subfamily - contains 1 ABC transmembrane type-1 domain - contains 1 ABC transporter domain Compartment: - endoplasmic reticulum membrane - transmembrane segments seem to form a pore in the membrane Expression: - induced by interferon gamma Polymorphism: - 4 common alleles are officially recognized: a) TAP2*0101 (TAP2A or PSF2A or RING11A) b) TAP2*0102 (TAP2E), c) TAP2*0103 (TAP2F) d) TAP2*0201 (TAP2B or PSF2B or RING11B) - other relatively common alleles have been identified: TAP2*01D, TAP2*01E, TAP2*01F, TAP2*01G, TAP2*01H, TAP2*02B, TAP2*02C (TAP2*0202), TAP2*02D, TAP2*02E, TAP2*02F, TAP2*03A & TAP2*04A - allele TAP2*Bky2 is commonly found only in the Japanese population Pathology: - defects in TAP2 are a cause of bare lymphocyte syndrome - allele TAP2*Bky2, commonly found only in the Japanese may be associated with susceptibility to Sjoegren syndrome

General

antigen peptide transporter (Transporter Associated with Antigen Processing, TAP) transmembrane 9 protein

Properties

SIZE: entity length = 686 aa MW = 76 kD COMPARTMENT: endoplasmic reticulum MOTIF: exoplasmic domain {1-6} transmembrane domain {7-27} cytoplasmic loop {28-56} transmembrane domain {57-77} exoplasmic loop {78-98} transmembrane domain {99-119} cytoplasmic loop {120-148} transmembrane domain {149-169} exoplasmic loop {170-187} transmembrane domain {188-208} cytoplasmic loop {209-266} transmembrane domain {267-287} exoplasmic loop {288-293} transmembrane domain {294-314} cytoplasmic loop {315-374} MOTIF: binding site SITE: 301-389 FOR-BINDING-OF: peptide transmembrane domain {375-395} exoplasmic loop {396-408} transmembrane domain {409-429} cytoplasmic domain {430-686} MOTIF: binding site SITE: 414-433 FOR-BINDING-OF: peptide ABC transporter {468-686} ATP-binding site NAME: ATP-binding site SITE: 503-510

Database Correlations

OMIM correlations UniProt Q03519 PFAM correlations

References

  1. Parham Nature 357:193 1992
  2. TAP2base; note=TAP2 mutation db http://bioinf.uta.fi/TAP2base/
  3. UniProt :accession Q03519

Component-of

TAP complex (MHC class 1 peptide loading complex)