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, multi-pass; Transporter; Membrane protein, integral
Cellular Component: endoplasmic reticulum membrane; integral to endoplasmic reticulum membrane; integral to membrane; membrane; mitochondrion; TAP complex
Molecular Function: ADP binding; ATP binding; ATPase activity, coupled to transmembrane movement of substances; MHC class I protein binding; peptide antigen binding; peptide transporter activity; peptide-transporting ATPase activity; protein binding; protein heterodimerization activity; protein homodimerization activity; TAP1 binding; TAP2 binding; tapasin binding
Biological Process: adaptive immune response; antigen processing and presentation of endogenous peptide antigen via MHC class I; antigen processing and presentation of endogenous peptide antigen via MHC class I via ER pathway, TAP-dependent; antigen processing and presentation of endogenous peptide antigen via MHC class Ib via ER pathway, TAP-dependent; antigen processing and presentation of exogenous protein antigen via MHC class Ib, TAP-dependent; antigen processing and presentation of peptide antigen via MHC class I; cytosol to ER transport; defense response; intracellular transport of viral proteins in host cell; metabolic process; peptide transport; positive regulation of antigen processing and presentation of peptide antigen via MHC class I; protection from natural killer cell mediated cytotoxicity; transmembrane transport
LTP: 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.