Biesecker L G, Giannola D M, Emerson S G
National Institutes of Health, National Center for Human Genome Research, Bethesda, Maryland 20892, USA.
Oncogene. 1995 Jun 1;10(11):2239-42.
Protein tyrosine kinase transmembrane receptors trigger signal transduction cascades upon ligand binding, resulting in cellular proliferation, differentiation, differentiation inhibition or apoptosis depending upon the cell target. The ETK2/TYRO3 receptor is a tyrosine kinase expressed in embryonic stem cells, brain and testis that has recently been cloned by several groups. Analysis of cDNA clones isolated from several tissues shows 2 isoforms of the Etk2/tyro3 gene product that result from usage of alternative exons near the 5' end of the gene. In addition, our data suggest that a third alternative exon is positioned between these two alternative exons. This novel exon encodes yet another isoform that predicts a unique amino-terminal protein sequence. The alternative exons (exons 2A, 2B and 2C), predict three isoforms with different initiation codons, signal sequences and lengths. The existence of these multiple isoforms may be important for protein processing, translocation, or function.
蛋白质酪氨酸激酶跨膜受体在配体结合后触发信号转导级联反应，根据细胞靶点的不同，导致细胞增殖、分化、分化抑制或凋亡。ETK2/TYRO3受体是一种在胚胎干细胞、脑和睾丸中表达的酪氨酸激酶，最近已被多个研究小组克隆。对从多个组织中分离的cDNA克隆的分析表明，Etk2/tyro3基因产物有两种异构体，这是由该基因5'端附近可变外显子的使用导致的。此外，我们的数据表明，第三个可变外显子位于这两个可变外显子之间。这个新的外显子编码另一种异构体，预测一个独特的氨基末端蛋白质序列。可变外显子（外显子2A、2B和2C）预测了三种具有不同起始密码子、信号序列和长度的异构体。这些多种异构体的存在可能对蛋白质加工、转运或功能很重要。
