Kotula L, Laury-Kleintop L D, Showe L, Sahr K, Linnenbach A J, Forget B, Curtis P J
Wistar Institute of Anatomy and Biology, Philadelphia, Pennsylvania 19104.
Genomics. 1991 Jan;9(1):131-40. doi: 10.1016/0888-7543(91)90230-c.
The human erythrocyte alpha-spectrin gene which spans 80 kbp has been cloned from human genomic DNA as overlapping lambda recombinants. The exon-intron junctions were identified and the exons mapped. The gene is encoded by 52 exons whose sizes range from 684 bp to the smallest of 18 bp. The donor and acceptor splice site sequences match the splice site consensus sequences, with the exception of one splice site where a donor sequence begins with -GC. The size and location of exons do not correlate with the 106-amino-acid repeat, except in three locations where the surrounding codons are conserved as well. The lack of correspondence between exons and 106-amino-acid repeat is interpreted to reflect the appearance of a spectrin-like gene from a minigene early in the evolution of eukaryotes. Since current evidence indicates that introns were present in genes before the divergence of prokaryotes and eukaryotes, it is possible that the original distribution of introns within the minigene has been lost by the random deletion of introns from the spectrin gene.
跨越80千碱基对的人类红细胞α-血影蛋白基因已从人类基因组DNA中作为重叠的λ重组体克隆出来。确定了外显子-内含子连接点并绘制了外显子图谱。该基因由52个外显子编码，其大小范围从684碱基对到最小的18碱基对。供体和受体剪接位点序列与剪接位点共有序列匹配，但有一个剪接位点的供体序列以-GC开头除外。外显子的大小和位置与106个氨基酸的重复序列不相关，只有在三个位置周围的密码子也保守的情况下除外。外显子与106个氨基酸重复序列之间缺乏对应关系被解释为反映了真核生物进化早期一个小基因中血影蛋白样基因的出现。由于目前的证据表明内含子在原核生物和真核生物分化之前就已存在于基因中，所以有可能血影蛋白基因中内含子的原始分布已因内含子从血影蛋白基因中的随机缺失而丢失。
