ABC transporter associated with antigen processing. In complex with TAP1 mediates unidirectional translocation of peptide antigens from cytosol to endoplasmic reticulum (ER) for loading onto MHC class I (MHCI) molecules (PubMed:25656091, PubMed:25377891). Uses the chemical energy of ATP to export peptides against the concentration gradient (PubMed:25377891). During the transport cycle alternates between 'inward-facing' state with peptide binding site facing the cytosol to 'outward-facing' state with peptide binding site facing the ER lumen. Peptide antigen binding to ATP-loaded TAP1-TAP2 induces a switch to hydrolysis-competent 'outward-facing' conformation ready for peptide loading onto nascent MHCI molecules. Subsequently ATP hydrolysis resets the transporter to the 'inward facing' state for a new cycle (PubMed:25377891, PubMed:25656091, PubMed:11274390). Typically transports intracellular peptide antigens of 8 to 13 amino acids that arise from cytosolic proteolysis via IFNG-induced immunoproteasome. Binds peptides with free N- and C-termini, the first three and the C-terminal residues being critical. Preferentially selects peptides having a highly hydrophobic residue at position 3 and hydrophobic or charged residues at the C-terminal anchor. Proline at position 2 has the most destabilizing effect (PubMed:7500034, PubMed:9256420, PubMed:11274390). As a component of the peptide loading complex (PLC), acts as a molecular scaffold essential for peptide-MHCI assembly and antigen presentation (PubMed:26611325, PubMed:1538751, PubMed:25377891). a peptide antigen(in) + ATP + H2O = a peptide antigen(out) + ADP + H(+) + phosphate Inhibited at high ER lumenal peptide concentrations. (Microbial infection) Inhibited by herpes simplex virus US12/ICP47 protein, which blocks the peptide-binding site of TAP1-TAP2. (Microbial infection) Inhibited by human cytomegalovirus US6 glycoprotein, which binds to the lumenal side of TAP1-TAP2 complex and inhibits peptide translocation by specifically blocking ATP-binding and preventing TAP1-TAP2 conformational rearrangement induced by peptide binding. Heterodimer of TAP1 and TAP2 (TAP1-TAP2) (PubMed:1538751). A component of the peptide loading complex (PLC), interacts via TAPBP with MHCI heterodimer; this interaction mediates peptide-MHCI assembly (PubMed:26611325). Recruits TAPBP in a 1:1 stoichiometry (PubMed:22638925). Interacts with classical MHCI such as HLA-A*02-B2M; this interaction is obligatory for the loading of peptide epitopes (PubMed:8805302, PubMed:8630735). Interacts with non-classical MHCI molecules including HLA-E-B2M and HLA-F-B2M as well as PLC component CALR before the peptide loading (PubMed:9427624, PubMed:10605026). (Microbial infection) Interacts with Epstein-Barr virus BLNF2a. (Microbial infection) Interacts with herpes simplex virus US12/ICP47. (Microbial infection) Interacts with adenovirus E3-19K glycoprotein, which binds TAP1-TAP2 and acts as a TAPBP inhibitor, preventing TAP1-TAP2 association with MHCI. The transmembrane segments seem to form a pore in the membrane. The peptide-binding site is shared between the cytoplasmic loops of TAP1 and TAP2. The nucleotide-binding domain (NBD) mediates ATP hydrolysis coupled to peptide translocation. Two ATP molecules are accommodated at distinct nucleotide binding sites (NBS) at TAP1-TAP2 dimer interface. Each NBS is formed by Walker A (GxxGxGKST) and Q-loop motifs from NBD of one subunit, while the NBD from the second subunit completes the active site by contributing the C loop motif (LSGGQ). Each ATP molecule is coordinated via the beta- and gamma-phosphates to a Mg2+ ion, which is necessary for ATP hydrolysis. 4 common alleles are officially recognized: TAP2*01:01 (TAP2A or PSF2A or RING11A), TAP2*01:02 (TAP2E), TAP2*01:03 (TAP2F), and TAP2*02:01 (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*02:02), TAP2*02D, TAP2*02E, TAP2*02F, TAP2*03A and TAP2*04A. The sequence shown is that of TAP2*01:01. The allele TAP2*Bky2 is commonly found only in the Japanese population. It may be associated with susceptibility to Sjoegren syndrome, an autoimmune disorder characterized by abnormal dryness of the conjunctiva, cornea and mouth due to exocrine glands dysfunction. The disease is caused by variants affecting the gene represented in this entry. Belongs to the ABC transporter superfamily. ABCB family. MHC peptide exporter (TC 3.A.1.209) subfamily. TAP2 mutation db Database for mutations in ABC proteins