Heemels M T, Schumacher T N, Wonigeit K, Ploegh H L
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Science. 1993 Dec 24;262(5142):2059-63. doi: 10.1126/science.8266106.
Major histocompatibility complex (MHC) class I molecules associate with peptides that are delivered from the cytosol to the lumen of the endoplasmic reticulum by the transporter associated with antigen processing (TAP). Liver microsomes of SHR and Lewis rats, which express different alleles of TAP (cim(b) and cim(a), respectively), accumulate different sets of peptides. Use of MHC congenic rats assigned this difference to the MHC, independent of the class I products expressed. Both the cim(a) and cim(b) TAP complexes translocate peptides with a hydrophobic carboxyl terminus, but translocation of peptides with a carboxyl-terminal His, Lys, or Arg residue is unique to cim(a). Thus, the specificity of the TAP peptide translocator restricts the peptides available for antigen presentation.
主要组织相容性复合体（MHC）I类分子与通过抗原加工相关转运体（TAP）从细胞质转运至内质网腔的肽段结合。自发性高血压大鼠（SHR）和刘易斯大鼠的肝微粒体分别表达不同的TAP等位基因（cim(b)和cim(a)），积累不同的肽段集合。使用MHC同基因大鼠将这种差异归因于MHC，而与所表达的I类产物无关。cim(a)和cim(b) TAP复合体都能转运具有疏水羧基末端的肽段，但具有羧基末端组氨酸、赖氨酸或精氨酸残基的肽段的转运是cim(a)所特有的。因此，TAP肽转运体的特异性限制了可用于抗原呈递的肽段。
