Tropomyosin, in association with the troponin complex, plays a central role in the calcium dependent regulation of muscle contraction. May also regulate motor systems required to maintain nuclear integrity and apico-basal polarity during embryogenesis.

(UniProt, P09491)

Homozygotes for Ifm(3)5 and Ifm(3)6 display characteristic departures from wild-type protein patterns in two-dimensional gels (Mogami and Hotta, 1981). Ifm(3)5 homozygotes lack myofibrils; Ifm(3)6 homozygotes have opaque strings of myofibrils. Both mutants are flightless as heterozygotes. The myofibrils of Ifm(3)6 heterozygotes are frayed.

Homozygous lethal; heterozygous flightless; interacts semilethally with heterozygous deficiency for Mlc2, i.e., Df(3R)99D3-E3.

Structural gene for tropomyosin that is active in particular muscle lineages in late embryos and adult flies (Basi et al., 1984). A dominant flightless mutant lfm(3)3 was induced by Mogami and Hotta (1981); this mutant, which was unable to jump or fly, turned out to be a Tm2 allele, Tm23. Although arranged in sarcomeres, the myofibrils of Tm23 are structurally weak (Karlik and Fyrberg, 1986). The flightless phenotype can be rescued by P-element mediated transformation with two copies of the wild-type allele of Tm2 (Fyrberg and Karlik, 1987); the ability to jump can be restored with one copy of Tm2+ (Tansey et al., 1987).