Yamazaki K, Okamura C, Ihara T, Yasumasu I
Department of Biology, School of Education, Waseda University, Tokyo, Japan.
Zoolog Sci. 1997 Jun;14(3):469-73. doi: 10.2108/zsj.14.469.
We have characterized the nucleotide sequence of Na+/K(+)-ATPase alpha subunit (NKA) cDNA in embryos of the sea urchin, Hemicentrotus pulcherrimus. The primer extension experiments showed that the sea urchin NKA gene generated multiple lengths of transcript. To obtain the 5'-ends of the transcripts, we isolated cDNA clones by the rapid amplification of cDNA ends (RACE). These clones were classified into 2 types on the basis of their 5' leader sequences. The sequences of the clones were identical except their 5' leaders. By Northern blot analysis, 1 of the 2 types of transcripts was always detectable in sea urchin embryos during early development, and another was not detected before the morula stage. Genomic PCR demonstrated that the two 5' leaders were coded by different exons separated by an intron in a single gene. These results show that the transcripts coding 2 isoforms were expressed from a single gene.
我们已经对海胆（Hemicentrotus pulcherrimus）胚胎中Na⁺/K⁺-ATP酶α亚基（NKA）的cDNA核苷酸序列进行了表征。引物延伸实验表明，海胆NKA基因产生了多种长度的转录本。为了获得转录本的5'端，我们通过cDNA末端快速扩增（RACE）分离了cDNA克隆。根据它们的5'前导序列，这些克隆被分为2种类型。除了5'前导序列外，这些克隆的序列是相同的。通过Northern印迹分析，在早期发育过程中，海胆胚胎中这2种类型的转录本中的1种总是可以检测到，而另一种在桑椹胚阶段之前未被检测到。基因组PCR表明，这两个5'前导序列由单个基因中被一个内含子隔开的不同外显子编码。这些结果表明，编码2种同工型的转录本是从单个基因表达的。
