a 'transporter associated with antigen processing' (TAP) protein. Member of the ATP binding cassette (ABC) family of transmembrane transporters. Also acts as a molecular scaffold for the final stage of MHC class I folding, namely the binding of peptide. Nascent MHC class I molecules associate with TAP via tapasin. Inhibited by the 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 and inhibits peptide translocation by specifically blocking ATP-binding to TAP1 and prevents the conformational rearrangement of TAP induced by peptide binding. Inhibited by human adenovirus E3-19K glycoprotein, which binds the TAP complex and acts as a tapasin inhibitor, preventing MHC class I/TAP association. Expression of TAP1 is down-regulated by human Epstein-Barr virus vIL-10 protein, thereby affecting the transport of peptides into the endoplasmic reticulum and subsequent peptide loading by MHC class I molecules. Defects in TAP1 are a cause of bare lymphocyte syndrome. Note: This description may include information from UniProtKB.
Protein type: Membrane protein, integral; Membrane protein, multi-pass; Transporter
Cellular Component: endoplasmic reticulum membrane; TAP complex; mitochondrial inner membrane; plasma membrane; integral to membrane; integral to endoplasmic reticulum membrane; cytosol
Molecular Function: tapasin binding; protein binding; protein homodimerization activity; peptide transporter activity; peptide antigen binding; TAP1 binding; MHC class I protein binding; TAP2 binding; oligopeptide-transporting ATPase activity; ADP binding; ATP binding
Biological Process: peptide transport; intracellular transport of viral proteins in host cell; antigen processing and presentation of peptide antigen via MHC class I; positive regulation of T cell mediated cytotoxicity; antigen processing and presentation of exogenous peptide antigen via MHC class I, TAP-dependent; antigen processing and presentation of exogenous peptide antigen via MHC class I; defense response; transmembrane transport; antigen processing and presentation of endogenous peptide antigen via MHC class I; cytosol to ER transport
SS: The number of records in which this modification site was determined using site-specific methods. SS methods include amino acid sequencing, site-directed mutagenesis, modification site-specific antibodies, specific MS strategies, etc.