Dasgupta P, Reddy E P
Wistar Institute, Philadelphia, Pennsylvania 19104.
Oncogene. 1989 Dec;4(12):1419-23.
The murine c-myb gene has been recently shown to code for two protein products of 75kd and 89kd. The 89kd protein appears to be generated from an alternatively spliced mRNA which contains an additional stretch of 363 bases between exons 9 and 10. In this communication, we have examined whether similar alternatively spliced mRNAs of c-myb occur in human cells. Human c-myb exon 9A has been identified and sequenced in a cDNA clone (ML5) generated from the acute myeloid leukemic cell line ML-2. This alternatively spliced exon of c-myb has been found to contain the same number of nucleotides (363bp) as the corresponding mouse exon. Between murine and human exon 9A sequences, 81% sequence homology was found at the DNA level, while the homology at the predicted amino acid level was found to be 73%. A stretch of 14 amino acid residues at the junction of exons 9A and 10 have been found to be conserved between Drosophila and human sequences indicating that this region might perform an essential biological function which was deemed necessary through evolution.
最近研究表明，鼠源c-myb基因编码75kd和89kd两种蛋白质产物。89kd蛋白似乎由一种选择性剪接的mRNA产生，该mRNA在第9外显子和第10外显子之间含有一段额外的363个碱基。在本报告中，我们研究了人类细胞中是否存在类似的c-myb选择性剪接mRNA。在从急性髓系白血病细胞系ML-2产生的cDNA克隆（ML5）中，已鉴定并测序了人类c-myb第9A外显子。已发现c-myb的这种选择性剪接外显子与相应的小鼠外显子含有相同数量的核苷酸（363bp）。在鼠源和人源第9A外显子序列之间，在DNA水平上发现有81%的序列同源性，而在预测的氨基酸水平上同源性为73%。已发现在果蝇和人类序列之间，第9A外显子和第10外显子交界处的一段14个氨基酸残基是保守的，这表明该区域可能执行一种通过进化被认为是必要的重要生物学功能。
