Wong S, Freeman J D, Kelleher C, Mager D, Takei F
Terry Fox Laboratory, British Columbia Cancer Research Centre, Vancouver, Canada.
J Immunol. 1991 Aug 15;147(4):1417-23.
Ly-49 (YE1/48, A1) is a dimer protein expressed on subpopulations of murine NK cells. It is a member of a superfamily of type II transmembrane proteins containing carbohydrate recognition domains (CRD). In the mouse genome, the detection of multiple restriction fragments that cross-hybridize with Ly-49 cDNA probes suggests the presence of related genes. In this study, we have isolated several genomic clones encoding portions of CRD sequences highly homologous to the CRD of Ly-49. By using primers based on the consensus sequences of the genomic clones, expression of Ly-49-related genes was detected by the polymerase chain reaction in various organs, including lung, kidney, liver, spleen, and thymus. Two full-length cDNA clones that are highly homologous to the Ly-49 gene were subsequently isolated from a lung cDNA library. At the nucleotide level, the two clones are 72% and 80% identical to Ly-49 in their translated regions, but their sequences are different from those of the genomic clones characterized to date. The two cDNA clones potentially encode type II transmembrane proteins containing CRD that are very similar to Ly-49. These amino acid sequences are also homologous to other members of the superfamily of CRD-containing type II transmembrane proteins, including hepatic lectins and the low affinity IgER (CD23). The homology is most evident in the CRD but is also significant in other domains. These results demonstrate the existence of several functional genes that are highly related to Ly-49. These genes comprise a subfamily within the superfamily of type II transmembrane proteins containing CRD.
Ly-49（YE1/48，A1）是一种在小鼠自然杀伤细胞亚群上表达的二聚体蛋白。它是包含碳水化合物识别结构域（CRD）的II型跨膜蛋白超家族的成员。在小鼠基因组中，与Ly-49 cDNA探针交叉杂交的多个限制性片段的检测表明存在相关基因。在本研究中，我们分离了几个基因组克隆，这些克隆编码与Ly-49的CRD序列高度同源的部分。通过使用基于基因组克隆共有序列的引物，利用聚合酶链反应在包括肺、肾、肝、脾和胸腺在内的各种器官中检测到Ly-49相关基因的表达。随后从肺cDNA文库中分离出两个与Ly-49基因高度同源的全长cDNA克隆。在核苷酸水平上，这两个克隆在其翻译区域与Ly-49的同一性分别为72%和80%，但它们的序列与迄今为止鉴定的基因组克隆不同。这两个cDNA克隆可能编码含有与Ly-49非常相似的CRD的II型跨膜蛋白。这些氨基酸序列也与含CRD的II型跨膜蛋白超家族的其他成员同源，包括肝凝集素和低亲和力IgER（CD23）。这种同源性在CRD中最为明显，但在其他结构域中也很显著。这些结果证明存在几个与Ly-49高度相关的功能基因。这些基因在包含CRD的II型跨膜蛋白超家族中构成一个亚家族。
