Recognition of foreign and dysregulated antigens by the cellular innate and adaptive immune systems is in large part dependent on the cell surface display of peptide/MHC (pMHC) complexes. The formation of such complexes requires the generation of antigenic peptides, proper folding of MHC molecules, loading of peptides onto MHC molecules, glycosylation, and transport to the plasma membrane. This complex series of biosynthetic, biochemical, and cell biological reactions is known as “antigen processing and presentation”. Here, we summarize recent work, focused on the structural and functional characterization of the key MHC-I-dedicated chaperones, tapasin, and TAPBPR. The mechanisms reflect the ability of conformationally flexible molecules to adapt to their ligands, and are comparable to similar processes that are exploited in peptide antigen loading in the MHC-II pathway.

细胞先天和适应性免疫系统对外源和失调抗原的识别在很大程度上取决于肽/ MHC（pMHC）复合物的细胞表面展示。这种复合物的形成需要抗原肽的产生，MHC分子的适当折叠，将肽负载到MHC分子上，糖基化和运输到质膜。这种复杂的生物合成，生化和细胞生物反应系列被称为“抗原加工和呈递”。在这里，我们总结了最近的工作，重点是MHC-I专用伴侣蛋白，塔帕森和TAPBPR的结构和功能表征。该机制反映了构象柔性分子适应其配体的能力，