Tepler I, Shimizu A, Leder P
Department of Genetics, Harvard Medical School, Howard Hughes Medical Institute, Boston, Massachusetts.
J Biol Chem. 1989 Apr 5;264(10):5912-5.
We have isolated and characterized the gene coding for the alpha subunit of the rat mast cell high affinity IgE receptor. The gene comprises five exons and four introns and spans approximately 6.6 kilobases. The leader sequence is encoded by two exons, the second of which is only 21 base pairs long. The third and fourth exons each code for repeating immunoglobulin-like extracellular domains. A hydrophobic transmembrane domain and positively charged cytoplasmic tail are encoded by a single final exon. The sequence of the 5'-flanking region was determined, and the major transcription initiation site was mapped. The structure of the gene suggests that two minor species of RNA produced by rat basophilic leukemia cells are due to alternative splicing. In one case, the small second exon is removed entirely, and, in the other, 163 base pairs at the 3' end of the fourth exon are removed. The latter species of RNA suggests the possibility of a secreted form of the alpha chain of the receptor. A third variant species of RNA, lacking a leader sequence, may be due to use of an alternative transcription initiation site.
我们已经分离并鉴定了编码大鼠肥大细胞高亲和力IgE受体α亚基的基因。该基因由五个外显子和四个内含子组成，跨度约为6.6千碱基。前导序列由两个外显子编码，其中第二个外显子仅21个碱基对长。第三和第四外显子各自编码重复的免疫球蛋白样细胞外结构域。一个疏水跨膜结构域和带正电荷的细胞质尾巴由单个最终外显子编码。确定了5'侧翼区域的序列，并绘制了主要转录起始位点。该基因的结构表明，大鼠嗜碱性白血病细胞产生的两种次要RNA物种是由于可变剪接。在一种情况下，小的第二个外显子被完全去除，而在另一种情况下，第四个外显子3'端的163个碱基对被去除。后一种RNA物种提示了受体α链分泌形式的可能性。第三种变异的RNA物种缺乏前导序列，可能是由于使用了替代转录起始位点。
