Karlik C C, Fyrberg E A
Mol Cell Biol. 1986 Jun;6(6):1965-73. doi: 10.1128/mcb.6.6.1965-1973.1986.
We compared the structure and function of the two Drosophila melanogaster tropomyosin genes. The most striking structural aspect was their size disparity. Codons 1 through 257 of gene 2 occupied 833 nucleotides and contained only one intron, whereas the corresponding region of gene 1 occupied 17.5 kilobases and was interrupted by eight introns. The intron-exon arrangement of gene 1 reflected evolutionary expansion of tropomyosin via 42- and 49-residue duplications, which are probably actin-binding domains. Functionally, gene 1 was considerably more complex than gene 2; it was active in both muscle and nonmuscle cell lineages, had at least five variable exons, and specified a minimum of five developmentally regulated isoforms. Two of these isoforms, which accumulated only in flight muscles, were unprecedented fusion proteins in which the tropomyosin sequence was joined to a carboxy-terminal proline-rich domain.
我们比较了两种黑腹果蝇原肌球蛋白基因的结构和功能。最显著的结构特征是它们的大小差异。基因2的第1至257个密码子占据833个核苷酸，仅含有一个内含子，而基因1的相应区域占据17.5千碱基，被8个内含子打断。基因1的内含子-外显子排列反映了原肌球蛋白通过42和49个残基重复的进化扩张，这些重复可能是肌动蛋白结合结构域。在功能上，基因1比基因2复杂得多；它在肌肉和非肌肉细胞谱系中均有活性，至少有五个可变外显子，并至少指定了五种发育调控的同工型。其中两种同工型仅在飞行肌中积累，是前所未有的融合蛋白，其中原肌球蛋白序列与富含脯氨酸的羧基末端结构域相连。
