Chan T A, Chu C A, Rauen K A, Kroiher M, Tatarewicz S M, Steele R E
Department of Biological Chemistry, University of California, Irvine 92717-1700.
Oncogene. 1994 Apr;9(4):1253-9.
Using the polymerase chain reaction with primers corresponding to conserved regions in the kinase domain of protein-tyrosine kinases, we amplified segments of several protein-tyrosine kinase genes from Hydra vulgaris, a member of the ancient metazoan phylum Cnidaria. Characterization of cDNA clones for one of these genes, HTK16, revealed that it encodes a non-receptor protein-tyrosine kinase with two SH2 domains but no SH3 domain. In this regard the predicted HTK16 protein resembles two mammalian non-receptor protein-tyrosine kinases, the products of the ZAP-70 and syk genes. However, the HTK16 protein contains five ankyrin-like repeats, a structural motif which has not previously been found in protein-tyrosine kinases. The HTK16 protein also contains a potential tyrosine phosphorylation site in its carboxyl-terminal tail which resembles the phosphorylation site in members of the src family. RNA hybridization analysis indicates that the HTK16 gene is expressed in epithelial cells, cells which also express the Hydra homologue of the src protein. Our finding of the HTK16 gene in Hydra indicates that diversification of genes encoding non-receptor protein-tyrosine kinases was a very early event in metazoan evolution.
利用聚合酶链反应，采用与蛋白酪氨酸激酶激酶结构域保守区域相对应的引物，我们从古老后生动物门刺胞动物的成员——普通水螅中扩增出了几个蛋白酪氨酸激酶基因的片段。对其中一个基因HTK16的cDNA克隆进行表征后发现，它编码一种非受体蛋白酪氨酸激酶，具有两个SH2结构域但没有SH3结构域。在这方面，预测的HTK16蛋白类似于两种哺乳动物非受体蛋白酪氨酸激酶，即ZAP - 70和syk基因的产物。然而，HTK16蛋白包含五个锚蛋白样重复序列，这是一种以前在蛋白酪氨酸激酶中未发现的结构基序。HTK16蛋白在其羧基末端尾巴中还含有一个潜在的酪氨酸磷酸化位点，该位点类似于src家族成员中的磷酸化位点。RNA杂交分析表明，HTK16基因在上皮细胞中表达，而上皮细胞也表达src蛋白的水螅同源物。我们在水螅中发现HTK16基因表明，编码非受体蛋白酪氨酸激酶的基因多样化是后生动物进化中非常早期的事件。
