The intracellular antigen transport machinery TAP in adaptive immunity and virus escape mechanisms.

The transporter associated with antigen processing (TAP) is a crucial element of the adaptive immune system, which translocates proteasomal degradation products into the endoplasmic reticulum, for transfer of these peptides on major histocompatibility complex (MHC) I molecules within a macromolecular peptide-loading complex. After loading and intracellular transport to the cell surface, these peptide/MHC complexes are monitored by cytotoxic T-lymphocytes. This review summarizes the structural organization and function of the ABC transporter TAP. Furthermore, we discuss human diseases and viral evasion strategies associated with TAP function.