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Gene Review

Tm2  -  Tropomyosin 2

Drosophila melanogaster

Synonyms: CG4843, DROTROPI1, Dmel\CG4843, IP16005p, Ifm(3)3, ...
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Disease relevance of Tm2


Psychiatry related information on Tm2

  • D53, a missense mutation, S185F, of the tropomyosin-2, Tm2, gene fully suppresses all the phenotypic effects of held-up(2), including the destructive hypercontraction of the indirect flight muscles (IFMs), a lack of jumping, the progressive myopathy of the walking muscles, and reductions in larval crawling and feeding behavior [1].

High impact information on Tm2


Biological context of Tm2

  • The S185F substitution in Tm2 is close to a troponin T binding site on tropomyosin [1].
  • Interestingly, in Apis mellifera (hymenopteran), while most of the Tm1 and Tm2 gene features are conserved, the gene lacks any C-terminal exons [6].
  • Dipteran genomes contain one tropomyosin gene that encodes one or two high-molecular weight isoforms (TmH) incorporating APPAEGA-rich sequences, specifically expressed in IFM [7].
  • Vertebrate nonmuscle cells, such as human and rat fibroblasts, express multiple isoforms of tropomyosin, which are generated from four different genes and a combination of alternative promoter activities and alternative splicing [8].
  • The differential expression of tropomyosin isoforms found in cell transformation and cell differentiation, as well as the differential localization of tropomyosin isoforms in some types of culture cells and developing neurons suggest a differential isoform function in vivo [8].

Anatomical context of Tm2

  • Using a quantitative in vitro motility assay we have found that the wild type Drosophila ACT88F actin behaved like rabbit skeletal muscle actin when tropomyosin and troponin were added at pCa5 and pCa9 [9].
  • The amount of GST-2 stably bound to the myofibril is directly proportional to the total amount of undigested TnH [10].
  • The thorax RNAs encode a new tropomyosin isoform resolved on two-dimensional gels [11].
  • The results of this analysis have allowed us to identify a region responsible for 20% of maximal TmI expression, estimate threshold levels of TmI RNA required for indirect flight and jump muscle function, and obtain evidence suggesting that sarcomere length may be an important determinant of flight muscle function [12].
  • cDNA clones encoding two isoforms of chicken gizzard calponin, a recently identified actin- and tropomyosin-binding protein, have been isolated and sequenced [13].

Associations of Tm2 with chemical compounds

  • Their N-termini are conventional and complete tropomyosin sequences, but their C-termini consist of different IFM-specific domains that are rich in proline, alanine, glycine and glutamate [6].
  • The positions of tropomyosin in the mutant filaments, in both the Ca(2+)-free and the Ca(2+)-induced states, were the same, and identical to that of wild-type filaments in the presence of Ca(2+) [14].
  • Aroclor 1254 and Cu(II) upregulated putative isoforms of tropomyosin and light chain of myosin [15].
  • 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 [16].
  • OBJECTIVE: To investigate this cross-reactivity in vitro, we have taken advantage of a complementary DNA that expresses tropomyosin, the immunodominant shrimp allergen [17].

Physical interactions of Tm2

  • The troponin was tightly bound to tropomyosin and could not be dissociated from it in non-denaturing conditions [18].

Regulatory relationships of Tm2


Other interactions of Tm2

  • Models to explain suppression by D53, derived from current knowledge of the vertebrate troponin-tropomyosin complex structure and functions, are discussed [1].
  • Tn-H is easily digested by calpain, suggesting that part of the molecule has an extended configuration [18].
  • The Drosophila sanpodo gene controls sibling cell fate and encodes a tropomodulin homolog, an actin/tropomyosin-associated protein [21].
  • When embryos were glycerinated and then treated with tropomyosin before fixation, actin filaments were well visualized as thicker, uniform-sized filaments, though the number of filaments decreased probably owing to glycerination [22].
  • A 21-residue peptide, obtained from endoproteinase Lys-C digested Pen a I by high-performance liquid chromatography, demonstrated significant homology (60-87%) with the muscle protein tropomyosin from various species and origins [23].

Analytical, diagnostic and therapeutic context of Tm2


  1. A tropomyosin-2 mutation suppresses a troponin I myopathy in Drosophila. Naimi, B., Harrison, A., Cummins, M., Nongthomba, U., Clark, S., Canal, I., Ferrus, A., Sparrow, J.C. Mol. Biol. Cell (2001) [Pubmed]
  2. Organization of contractile protein genes within the 88F subdivision of the D. melanogaster third chromosome. Karlik, C.C., Mahaffey, J.W., Coutu, M.D., Fyrberg, E.A. Cell (1984) [Pubmed]
  3. Alterations in flight muscle ultrastructure and function in Drosophila tropomyosin mutants. Kreuz, A.J., Simcox, A., Maughan, D. J. Cell Biol. (1996) [Pubmed]
  4. Lack of Drosophila cytoskeletal tropomyosin affects head morphogenesis and the accumulation of oskar mRNA required for germ cell formation. Tetzlaff, M.T., Jäckle, H., Pankratz, M.J. EMBO J. (1996) [Pubmed]
  5. Mutations in genes encoding fast-twitch contractile proteins cause distal arthrogryposis syndromes. Sung, S.S., Brassington, A.M., Grannatt, K., Rutherford, A., Whitby, F.G., Krakowiak, P.A., Jorde, L.B., Carey, J.C., Bamshad, M. Am. J. Hum. Genet. (2003) [Pubmed]
  6. The structural role of high molecular weight tropomyosins in dipteran indirect flight muscle and the effect of phosphorylation. Mateos, J., Herranz, R., Domingo, A., Sparrow, J., Marco, R. J. Muscle Res. Cell. Motil. (2006) [Pubmed]
  7. The coevolution of insect muscle TpnT and TpnI gene isoforms. Herranz, R., Mateos, J., Mas, J.A., García-Zaragoza, E., Cervera, M., Marco, R. Mol. Biol. Evol. (2005) [Pubmed]
  8. Tropomyosin isoforms in nonmuscle cells. Lin, J.J., Warren, K.S., Wamboldt, D.D., Wang, T., Lin, J.L. Int. Rev. Cytol. (1997) [Pubmed]
  9. Tropomyosin and troponin regulation of wild type and E93K mutant actin filaments from Drosophila flight muscle. Charge reversal on actin changes actin-tropomyosin from on to off state. Bing, W., Razzaq, A., Sparrow, J., Marston, S. J. Biol. Chem. (1998) [Pubmed]
  10. Interaction of troponin-H and glutathione S-transferase-2 in the indirect flight muscles of Drosophila melanogaster. Clayton, J.D., Cripps, R.M., Sparrow, J.C., Bullard, B. J. Muscle Res. Cell. Motil. (1998) [Pubmed]
  11. Alternative splicing of a Drosophila tropomyosin gene generates muscle tropomyosin isoforms with different carboxy-terminal ends. Basi, G.S., Boardman, M., Storti, R.V. Mol. Cell. Biol. (1984) [Pubmed]
  12. Small differences in Drosophila tropomyosin expression have significant effects on muscle function. Tansey, T., Schultz, J.R., Miller, R.C., Storti, R.V. Mol. Cell. Biol. (1991) [Pubmed]
  13. Molecular cloning and sequence analysis of smooth muscle calponin. Takahashi, K., Nadal-Ginard, B. J. Biol. Chem. (1991) [Pubmed]
  14. Drosophila muscle regulation characterized by electron microscopy and three-dimensional reconstruction of thin filament mutants. Cammarato, A., Hatch, V., Saide, J., Craig, R., Sparrow, J.C., Tobacman, L.S., Lehman, W. Biophys. J. (2004) [Pubmed]
  15. Changes in protein expression profiles in bivalve molluscs (Chamaelea gallina) exposed to four model environmental pollutants. Rodríguez-Ortega, M.J., Grøsvik, B.E., Rodríguez-Ariza, A., Goksøyr, A., López-Barea, J. Proteomics (2003) [Pubmed]
  16. Two Drosophila melanogaster tropomyosin genes: structural and functional aspects. Karlik, C.C., Fyrberg, E.A. Mol. Cell. Biol. (1986) [Pubmed]
  17. IgE reactivity against a cross-reactive allergen in crustacea and mollusca: evidence for tropomyosin as the common allergen. Leung, P.S., Chow, W.K., Duffey, S., Kwan, H.S., Gershwin, M.E., Chu, K.H. J. Allergy Clin. Immunol. (1996) [Pubmed]
  18. Troponin of asynchronous flight muscle. Bullard, B., Leonard, K., Larkins, A., Butcher, G., Karlik, C., Fyrberg, E. J. Mol. Biol. (1988) [Pubmed]
  19. PDP1, a novel Drosophila PAR domain bZIP transcription factor expressed in developing mesoderm, endoderm and ectoderm, is a transcriptional regulator of somatic muscle genes. Lin, S.C., Lin, M.H., Horváth, P., Reddy, K.L., Storti, R.V. Development (1997) [Pubmed]
  20. Myocyte-specific enhancer factor 2 acts cooperatively with a muscle activator region to regulate Drosophila tropomyosin gene muscle expression. Lin, M.H., Nguyen, H.T., Dybala, C., Storti, R.V. Proc. Natl. Acad. Sci. U.S.A. (1996) [Pubmed]
  21. The Drosophila sanpodo gene controls sibling cell fate and encodes a tropomodulin homolog, an actin/tropomyosin-associated protein. Dye, C.A., Lee, J.K., Atkinson, R.C., Brewster, R., Han, P.L., Bellen, H.J. Development (1998) [Pubmed]
  22. Electron microscopic visualization of actin filaments in the early embryo of Drosophila melanogaster: the use of phalloidin and tropomyosin. Katoh, K., Ichikawa, H., Ishikawa, H. Journal of electron microscopy. (1991) [Pubmed]
  23. Identification of the major brown shrimp (Penaeus aztecus) allergen as the muscle protein tropomyosin. Daul, C.B., Slattery, M., Reese, G., Lehrer, S.B. Int. Arch. Allergy Immunol. (1994) [Pubmed]
  24. Characterization of cDNA clones coding for muscle tropomyosin of the nematode Trichostrongylus colubriformis. Frenkel, M.J., Savin, K.W., Bakker, R.E., Ward, C.W. Mol. Biochem. Parasitol. (1989) [Pubmed]
  25. Effects of tropomyosin deficiency in flight muscle of Drosophila melanogaster. Molloy, J., Kreuz, A., Miller, R., Tansey, T., Maughan, D. Adv. Exp. Med. Biol. (1993) [Pubmed]
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