9n66
From Proteopedia
Transporter associated with antigen processing (TAP) bound to ATP and ADP in the outward-facing open state
Structural highlights
DiseaseTAP1_HUMAN Defects in TAP1 are a cause of bare lymphocyte syndrome type 1 (BLS1) [MIM:604571; also called HLA class I deficiency. BLS1 is a class I antigen deficiency that is not accompanied by particular pathologic manifestations during the first years of life. Systemic infections have not been described. Chronic bacterial infections, often beginning in the first decade of life, are restricted to the respiratory tract.[1] FunctionTAP1_HUMAN Involved in the transport of antigens from the cytoplasm to the endoplasmic reticulum for association with MHC class I molecules. 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. References
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Categories: Homo sapiens | Large Structures | Chen J | Lee J | Manon V
