Institut National de la Santé et de le Recherche Médicale, Unité 1013, Hôpital Necker, Paris, France.
Mol Immunol. 2013 Sep;55(2):153-5. doi: 10.1016/j.molimm.2012.10.013. Epub 2012 Nov 2.
Peptide epitopes presented by MHC class I molecules are produced through sequential proteolysis, frequently terminating with an aminoterminal trimming step. While the trimming enzymes processing endogenous MHC class I ligands in the endoplasmic reticulum have by now been characterized extensively, we have only recently identified an endosomal enzyme, insulin-regulated aminopeptidase (IRAP) that can trim cross-presented peptides derived from proteins internalized by dendritic cells. Here we summarize the essential features of IRAP as a trimming enzyme, propose an updated model of cellular cross-presentation pathways, and discuss potential additional functions of IRAP and its compartment in dendritic cell biology.
MHC Ⅰ类分子呈递的肽表位是通过连续的蛋白水解产生的，通常以氨基末端修剪步骤结束。虽然目前已经广泛描述了在内质网中加工内源性 MHC Ⅰ类配体的修剪酶，但我们最近才鉴定出一种内体酶，即胰岛素调节氨基肽酶（IRAP），它可以修剪树突状细胞内吞的蛋白质衍生的交叉呈递肽。在这里，我们总结了 IRAP 作为修剪酶的基本特征，提出了一个更新的细胞交叉呈递途径模型，并讨论了 IRAP 及其在树突状细胞生物学中的隔室的潜在其他功能。
