TAP complex (MHC class 1 peptide loading complex)

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Function

pump which delivers peptides to class 1 MHC molecules within the endoplasmic reticulum of antigen presenting cells
role in the transport of antigens from the cytoplasm to the endoplasmic reticulum for association with MHC class 1 molecules
acts as a molecular scaffold for final stage of MHC class 1 folding, binding of peptide
nascent MHC class 1 molecules associate with TAP via tapasin
inhibited by covalent attachment of herpes simplex virus ICP47 protein, which blocks peptide-binding site of TAP
inhibited by human cytomegalovirus US6 glycoprotein, which binds to the lumenal side of the TAP complex & inhibits peptide translocation by specifically blocking ATP-binding to TAP1 & prevents the conformational rearrangement of TAP induced by peptide binding
inhibited by human adenovirus E3-19K glycoprotein, which binds the TAP complex & acts as a tapasin inhibitor, preventing MHC class 1/TAP association
heterodimer of TAP1 & TAP2