Steele R E, Unger T F, Mardis M J, Fero J B
Department of Biological Chemistry, University of California, Irvine 92717.
J Biol Chem. 1989 Jun 25;264(18):10649-53.
The haploid genome of Xenopus laevis contains two src genes, and transcripts from both genes are found in the maternal RNA pool of the oocyte (Steele, R. E. (1985) Nucleic Acids Res. 13, 1747-1761). We have now isolated cDNA clones which contain complete coding sequences from both src mRNAs. In vitro translation of RNAs transcribed in vitro from these clones produces in each case a protein with an apparent molecular mass of 57 kDa. The in vitro-synthesized proteins show identical protease cleavage patterns. Sequence analysis of the coding regions of the two cDNAs revealed that they both produce 532-amino acid polypeptides which differ from each other at only eight sites. Analysis of silent site changes between the two coding sequences suggests that the two genes began diverging about 25 million years ago. Hybridization with probes specific for each of the two src RNAs indicates that the two genes are co-expressed in embryos and in at least some adult tissues as well as during oogenesis. Finally, expression of each of the cDNA clones in yeast causes the appearance of proteins which are recognized by an antibody which binds to phosphotryosine.
非洲爪蟾的单倍体基因组包含两个src基因，在卵母细胞的母源RNA库中可发现这两个基因的转录本（斯蒂尔，R.E.（1985年）《核酸研究》13卷，1747 - 1761页）。我们现已分离出包含两个src mRNA完整编码序列的cDNA克隆。从这些克隆体外转录的RNA进行体外翻译，在每种情况下都产生一种表观分子量为57 kDa的蛋白质。体外合成的蛋白质显示出相同的蛋白酶切割模式。对这两个cDNA编码区的序列分析表明，它们都产生532个氨基酸的多肽，彼此之间仅在8个位点存在差异。对这两个编码序列间沉默位点变化的分析表明，这两个基因大约在2500万年前开始分化。用针对两个src RNA中每一个的特异性探针进行杂交表明，这两个基因在胚胎、至少一些成年组织以及卵子发生过程中共同表达。最后，每个cDNA克隆在酵母中的表达导致出现能被结合磷酸酪氨酸的抗体识别的蛋白质。
