Characterization of Rae-1, early embryo-specific membrane protein

Rae-1cDNA是小鼠胚胎癌F9细胞中的一个视黄酸（RA）诱导的cDNA克隆。Rae-1 mRNA在成年小鼠组织中未检测到，但在早期小鼠胚胎中检测到，特别是在10天胚胎脑的额叶部分，其蛋白质的一级结构与主要组织相容性复合体（MHC）I类分子有较弱但显著的同源性。我们分别用磷脂酰肌醇特异性磷脂酶C（PI-PLC）和糖基化抑制剂衣霉素证实RAE-1是一种GPI锚定的细胞表面糖蛋白。此外，还鉴定了至少三种不同种类的Rae-1 cDNA（α、β和γ），并且这些cDNA之间的总体核苷酸序列同源性约为98%。结果发现，rae 1-alpha基因与rae 1-beta，gamma基因的表达模式存在差异，这可能与rae 1-alpha基因5 '上游区域与rae 1-beta，gamma基因不同的结构特征有关。GPI锚定的细胞表面糖蛋白。它们构成了一个新的基因家族，可能参与早期哺乳动物发育过程中的细胞-细胞相互作用。

Rae-1 cDNA is one of the retinoic acid (RA) -inducible cDNA clones in mouse embryonal carcinoma F9 cells. Rae-1 mRNAs were not detected in adult mouse tissues, but were detected in early mouse embryos, sepecially in the frontal part of the 10-day-embryo brain.The primary structure of RAE-1 protein has a weak, but significant homology with major histocompatibility complex (MHC) class I molecules. We confirmed that RAE-1 is a GPI-anchored and cell surface glycoprotein, using phosphatidyl inositol-spesific phospholipase C (PI-PLC) and inhibitor of glycosylation, tunicamycin, respectively. Furthermore, at least three different kinds of Rae-1 cDNAs (alpha, beta and gamma) were identified and the overall nucleotide sequence homology among these cDNAs was about 98%. Then, we isolated three kinds of the corresponding genes and mapped these genes on mouse chromosome 10A4 region by FISH.Interestingly, expression patterns were different between rae1-alpha and rae1-beta, gamma genes, which was considered to be correlated with the structural features that 5'-upstream region of rae1-alpha gene was different from that of rae1-beta, gamma genes.The rae-1 genes encode early-embryo specific, GPI-anchored cell surface glyoproteins. They constitute a novel gene family which may be involved in cell-cell interactions during early mammalian development.