Pierre P, Denzin L K, Hammond C, Drake J R, Amigorena S, Cresswell P, Mellman I
Department of Cell Biology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520-8002, USA.
Immunity. 1996 Mar;4(3):229-39. doi: 10.1016/s1074-7613(00)80431-8.
HLA-DM molecules remove invariant (Ii) chain peptides from newly synthesized MHC class II complexes. Their localization may thus delineate compartments, e.g., MIIC, specialized for loading peptides onto class II molecules. In murine A20 B cells, however, DM is not restricted to specialized endosomal class II-containing vesicles (CIIV). Although DM was found in CIIV, it was also found throughout the endocytic pathway, principally in lysosomes devoid of class II molecules. In human lymphoblasts, HLA-DM was found in structures indistinguishable from late endosomes or lysosomes, although in these cells the lysosomes contained MHC class II molecules. Thus, the distribution of HLA-DM does not necessarily identify specialized class II compartments. Many "MIIC" may represent conventional lysosomes that accumulate MHC class II and HLA-DM in a number of cell types.
HLA-DM分子从新合成的MHC II类复合物中去除恒定链（Ii）肽。因此，它们的定位可能描绘出专门用于将肽加载到II类分子上的区室，例如MIIC。然而，在鼠A20 B细胞中，DM并不局限于含有II类分子的特殊内体囊泡（CIIV）。尽管在CIIV中发现了DM，但在整个内吞途径中也发现了它，主要存在于不含II类分子的溶酶体中。在人淋巴母细胞中，HLA-DM存在于与晚期内体或溶酶体无法区分的结构中，尽管在这些细胞中溶酶体含有MHC II类分子。因此，HLA-DM的分布不一定能识别专门的II类区室。许多“MIIC”可能代表在多种细胞类型中积累MHC II类分子和HLA-DM的传统溶酶体。
