Angenieux C, Salamero J, Fricker D, Cazenave J P, Goud B, Hanau D, de La Salle H
Equipe Propre INSERM 99-08 and Unité INSERM 311, Etablissement Français du Sang-Alsace, Strasbourg 67065, France and UMR CNRS 144, Institut Curie, Paris 75005, France.
J Biol Chem. 2000 Dec 1;275(48):37757-64. doi: 10.1074/jbc.M007082200.
Dendritic cells express several alternatively spliced CD1e mRNAs. These molecules encode proteins characterized by the presence of either one, two, or three alpha domains and either a 51- or 63-amino acid cytoplasmic domain. Moreover, mRNAs encoding isoforms lacking the transmembrane domain are observed. Several of these CD1e isoforms were expressed in transfected cells, and two of them, with three alpha domains, displayed a particular processing pathway. These latter isoforms slowly leave the endoplasmic reticulum due to the presence of atypical dilysine motifs in the cytoplasmic tail. These molecules are associated with the beta(2)-microglobulin and accumulate in late Golgi and late endosomal compartments. In the latter compartments, they are cleaved into soluble forms that appear to be stable. In dendritic cells, these isoforms are mainly located in the Golgi apparatus, and upon maturation they are redistributed to late endosomal compartments. This work demonstrates the existence of CD1e molecules. As compared with other CD1 molecules, CD1e displays fundamentally different properties and therefore may represent a third type of CD1 molecules.
树突状细胞表达几种可变剪接的CD1e mRNA。这些分子编码的蛋白质的特征是存在一个、两个或三个α结构域以及一个51或63个氨基酸的胞质结构域。此外，还观察到编码缺乏跨膜结构域的异构体的mRNA。其中几种CD1e异构体在转染细胞中表达，其中两种具有三个α结构域的异构体表现出特定的加工途径。由于胞质尾部存在非典型双赖氨酸基序，后一种异构体缓慢离开内质网。这些分子与β2微球蛋白相关，并积聚在晚期高尔基体和晚期内体区室中。在后者的区室中，它们被切割成似乎稳定的可溶性形式。在树突状细胞中，这些异构体主要位于高尔基体中，成熟时它们会重新分布到晚期内体区室中。这项工作证明了CD1e分子的存在。与其他CD1分子相比，CD1e表现出根本不同的特性，因此可能代表第三种类型的CD1分子。
