Miller R C, Schaaf R, Maughan D W, Tansey T R
Department of Biology, Georgetown University, Washington, DC 20057.
J Muscle Res Cell Motil. 1993 Feb;14(1):85-98. doi: 10.1007/BF00132183.
The tropomyosin I(TmI) gene of Drosophila melanogaster encodes two isoforms of tropomyosin. The Ifm-TmI isoform is expressed only in indirect flight and jump muscles; the Scm-TmI isoform is found in other muscles of the larva and adult. The level of Ifm-TmI is severely reduced in the flightless mutant Ifm(3)3, which also is unable to jump. To explore the functional significance of tropomyosin isoform diversity in Drosophila, we have used P element-mediated transformation to express Scm-TmI in the indirect flight and jump muscles of Ifm(3)3 flies. Transformants gained the ability to jump and fly. The mechanical properties of isolated indirect flight muscle myofibres, and the ultrastructure of indirect flight and jump muscles from the transformants were comparable to wildtype. Thus, the Scm-TmI isoform can successfully substitute for Ifm-TmI in the indirect flight and jump muscles of the Ifm(3)3 strain.
黑腹果蝇的原肌球蛋白I（TmI）基因编码两种原肌球蛋白异构体。Ifm-TmI异构体仅在间接飞行肌和跳跃肌中表达；Scm-TmI异构体存在于幼虫和成虫的其他肌肉中。在无法飞行的突变体Ifm(3)3中，Ifm-TmI的水平严重降低，该突变体也无法跳跃。为了探究果蝇中原肌球蛋白异构体多样性的功能意义，我们利用P因子介导的转化，在Ifm(3)3果蝇的间接飞行肌和跳跃肌中表达Scm-TmI。转化体获得了跳跃和飞行的能力。分离出的间接飞行肌肌纤维的力学特性，以及转化体的间接飞行肌和跳跃肌的超微结构与野生型相当。因此，Scm-TmI异构体可以在Ifm(3)3品系的间接飞行肌和跳跃肌中成功替代Ifm-TmI。
