| Function | ABC transporter associated with antigen processing. In complex with TAP2 mediates unidirectional translocation of peptide antigens from cytosol to endoplasmic reticulum (ER) for loading onto MHC class I (MHCI) molecules. Uses the chemical energy of ATP to export peptides against the concentration gradient. 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. 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. As a component of the peptide loading complex (PLC), acts as a molecular scaffold essential for peptide-MHCI assembly and antigen presentation. |
| Protein Name | Antigen Peptide Transporter 1Apt1Atp-Binding Cassette Sub-Family B Member 2Peptide Supply Factor 1Peptide Transporter Psf1Psf-1Peptide Transporter Tap1Peptide Transporter Involved In Antigen Processing 1Really Interesting New Gene 4 ProteinRing4 |
| Database Links | Reactome: R-HSA-1236974Reactome: R-HSA-983170 |
| Cellular Localisation | Endoplasmic Reticulum MembraneMulti-Pass Membrane ProteinThe Transmembrane Segments Seem To Form A Pore In The Membrane |
| Alternative Protein Names | Antigen Peptide Transporter 1 proteinApt1 proteinAtp-Binding Cassette Sub-Family B Member 2 proteinPeptide Supply Factor 1 proteinPeptide Transporter Psf1 proteinPsf-1 proteinPeptide Transporter Tap1 proteinPeptide Transporter Involved In Antigen Processing 1 proteinReally Interesting New Gene 4 Protein proteinRing4 proteinTAP1 proteinABCB2 proteinPSF1 proteinRING4 proteinY3 protein |
Information sourced from Uniprot.org
