Hendriks W, Leunissen J, Nevo E, Bloemendal H, de Jong W W
Proc Natl Acad Sci U S A. 1987 Aug;84(15):5320-4. doi: 10.1073/pnas.84.15.5320.
The complete structure of the single-copy alpha A-crystallin gene of the blind mole rat (Spalax ehrenbergi) has been determined in order to elucidate the evolutionary effects of the loss of vision on a lens-specific protein and its gene. The alpha A-crystallin gene appears to have all the necessary transcriptional and translational signal sequences to be expressed in the rudimentary lens of the mole rat and gives rise to probably two protein products by means of alternative splicing, as in rodents with normal vision. Comparisons of the blind mole rat alpha A-crystallin sequence with alpha A sequences from other rodents reveal a considerable acceleration of the substitution rate at nonsynonymous positions in the mole rate lineage, which reflects a relaxation of selective constraints, but the acceleration is not to the extent that might be expected if the gene were now without any function. The remaining evolutionary constraints still imposed upon the mole rat alpha A-crystallin gene may possibly reflect the need for alpha-crystallin expression as an indispensable component in the developmental program of the atrophied eye.
为了阐明视力丧失对晶状体特异性蛋白质及其基因的进化影响，已确定了盲鼹鼠（Spalax ehrenbergi）单拷贝αA-晶状体蛋白基因的完整结构。与具有正常视力的啮齿动物一样，αA-晶状体蛋白基因似乎具有在鼹鼠发育不全的晶状体中表达所需的所有转录和翻译信号序列，并可能通过可变剪接产生两种蛋白质产物。将盲鼹鼠αA-晶状体蛋白序列与其他啮齿动物的αA序列进行比较，发现在鼹鼠谱系中非同义位点的替换率有相当大的加速，这反映了选择限制的放松，但这种加速程度并非该基因现在可能没有任何功能时所预期的那样。仍然施加在鼹鼠αA-晶状体蛋白基因上的其余进化限制可能反映了α-晶状体蛋白表达作为萎缩眼睛发育程序中不可或缺的组成部分的必要性。
