Transporter Associated with Antigen Processing; antigen peptide transporter-1; peptide transporter TAP1, peptide transporter PSF1, peptide supply factor 1; PSF-1 (TAP1, APT1, RING4, Y3, MTP-1, HAM-1)

^[1]^[2]^[3]

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, namely the 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 the 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
expression of TAP1 is down-regulated by human Epstein-Barr virus vIL-10 protein, thereby affecting transport of peptides into the endoplasmic reticulum & subsequent peptide loading by MHC class 1 molecules
heterodimer of TAP1 & TAP2

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

induced by interferon gamma polymorphism
five common alleles; TAP1*0101 (PSF1A), TAP1*0201 (PSF1B), TAP1*0301 (PSF1C), TAP1*0104 & TAP1*x