TAP1 : transporter 1, ATP binding cassette subfamily B member
Description
The TAP1 (transporter 1, ATP binding cassette subfamily B member) is a protein-coding gene located on chromosome 6.
The TAP1 gene provides instructions for making a protein that plays an important role in the immune system. The TAP1 protein assembles with another protein called TAP2 (produced from the TAP2 gene) to form a protein complex called transporter associated with antigen processing (TAP) complex. This complex, which is found in the membrane of a cell structure called the endoplasmic reticulum, moves (transports) protein fragments (peptides) from foreign invaders into the endoplasmic reticulum. There, the peptides are attached to major histocompatibility complex (MHC) class I proteins. The peptide-bound MHC class I proteins are then moved to the surface of the cell so that specialized immune system cells can interact with them. When these immune system cells recognize the peptides as harmful, they launch an immune response to get rid of the foreign invaders.
The TAP1 protein, in collaboration with TAP2, forms the transporter associated with antigen processing (TAP) complex. This complex acts as a molecular scaffold in the endoplasmic reticulum (ER) membrane, transporting peptide antigens from the cytosol into the ER lumen for loading onto MHC class I molecules. It harnesses ATP energy to pump these peptides against the concentration gradient. During the transport cycle, TAP1-TAP2 transitions between inward-facing and outward-facing conformations, binding peptides with free N- and C-termini, favoring those with hydrophobic residues at position 3 and hydrophobic or charged residues at the C-terminus. The complex's interaction with TAPBP facilitates peptide-MHC I assembly, ultimately contributing to antigen presentation.
TAP1 is also known as ABC17, ABCB2, APT1, D6S114E, MHC1D1, PSF-1, PSF1, RING4, TAP1*0102N, TAP1N.
