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Gene Review

Mhc  -  Myosin heavy chain

Drosophila melanogaster

Synonyms: Bsh, CG17927, DROMHC, Dm II, DmMHC, ...
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Disease relevance of Mhc


Psychiatry related information on Mhc


High impact information on Mhc

  • Myosin motor proteins use the energy derived from ATP hydrolysis to move cargo along actin tracks [4].
  • The role of actin isoforms has received little attention, largely because of the lack of a suitable cell type in which the myosin isoform remains constant yet the actin isoforms vary [5].
  • How this myosin might orient the left-right axis has began to be elucidated by showing that it interacts directly with beta-catenin, suggesting that myosin ID interacts with the adherens junction to control the direction of organ looping [6].
  • This is the first demonstration of a role of a myosin in body patterning [6].
  • The identification of multiple isoforms of nonmuscle myosin-II, whose activities and regulation differ from that of smooth muscle myosin-II, suggests that, in addition to regulatory light chain phosphorylation, other regulatory mechanisms control vertebrate nonmuscle myosin-II activity [7].

Biological context of Mhc

  • These mutants are caused by single point mutations in the ATP binding/hydrolysis domain of Mhc and lead to degeneration of the flight muscles [1].
  • We show in this paper that neither sarcomeric myosin nor actin are required for myoblast fusion or the subsequent morphogenesis of muscle fibres, i.e. fibre morphogenesis does not depend on myofibrillogenesis [8].
  • A portion of the Drosophila melanogaster MHC hinge is encoded by mutually exclusive alternative exons 15a and 15b, the use of which correlates with fast (hinge A) or slow (hinge B) muscle physiological properties [9].
  • The GFP-tagged Myosin V1 rescued the male sterile phenotype of Jaguar showing it is functional in vivo [10].
  • Comparison of the minimal promoter to Mhc genes of 10 Drosophila species identified putative regulatory elements in the upstream region and in the first intron [11].

Anatomical context of Mhc


Associations of Mhc with chemical compounds

  • However, the NH2-terminal 12 residues show similarity to the NH2-terminal sequence of actin, a region that interacts with myosin [15].
  • The myosin heavy and light chain genes, the actin genes, the troponin genes, and the atrial natriuretic factor and muscle creatine kinase genes have served as excellent paradigms for the study of cardiac gene expression [16].
  • A clone of a fast isoform of myosin heavy chain (HC) gene was isolated from a cDNA1 expression library made from mRNA purified from the deep abdominal flexor muscle of the lobster, Homarus americanus [17].
  • Aroclor 1254 and Cu(II) upregulated putative isoforms of tropomyosin and light chain of myosin [18].

Physical interactions of Mhc

  • Here, two different solid-state binding assays demonstrate that flightin binds to myosin and to a recombinant fragment of the myosin rod that include the COOH-terminal 600 amino acids (zone 19 to tail piece) [19].
  • Electron microscopy of isolated thick filaments and of myosin molecules suggests that the molecules are flexible, but myosin fragments and crossbridges have been reported not to interact with inappropriately oriented actin filaments [20].
  • We describe the properties of a hybrid protein comprising the full length of the Xenopus laevis calmodulin sequence, followed by a pentapeptide linker (GGGGS), and residues 3-26 of M13, the calmodulin binding region of skeletal muscle myosin light chain kinase [21].

Enzymatic interactions of Mhc

  • The mutations are associated with age-dependent, site-specific degradation of myosin heavy chain and failure to accumulate phosphorylated forms of flightin, an indirect flight muscle-specific protein previously localized to the thick filament [22].

Regulatory relationships of Mhc

  • Mutations in the myosin heavy-chain gene that prevent thick filament assembly block accumulation of all flightin variants except N1, the unphosphorylated precursor, which is present at much reduced levels [23].
  • In addition, we identified previously uncharacterized proteins with putative actin-interaction domains that are up-regulated in Mhc mutants and differentially expressed in muscles [14].
  • Specific myosin heavy chain mutations suppress troponin I defects in Drosophila muscles [24].
  • Exchanging the flight muscle-specific exon 3 region into the embryonic isoform increased actin sliding velocity 3-fold and improved indirect flight muscle ultrastructure integrity but failed to rescue the flightless phenotype of flies expressing embryonic myosin [25].

Other interactions of Mhc

  • Characterization of these new Mhc alleles suggests that hypercontraction occurs via a mechanism, which is molecularly distinct from mutants identified previously in troponin I and troponin T [1].
  • Previously, we exchanged two versions of this region (encoded by alternative exon 7s) between the indirect flight muscle myosin isoform (IFI) and an embryonic myosin isoform (EMB) and found, surprisingly, that in vitro solution actin-activated ATPase rates were increased (higher Vmax) by both exon exchanges [26].
  • In intact muscles flightin is associated with the A band of the sarcomere, where evidence suggests it interacts with the myosin filaments [15].
  • The nonmuscle myosin II heavy chain (MHC encoded by zipper is required for cell sheet movements in Drosophila embryos [27].
  • Decoration of the thin filaments with myosin subfragment-1 in rigor conditions appeared not to be affected by the troponin [28].

Analytical, diagnostic and therapeutic context of Mhc


  1. Characterization of a hypercontraction-induced myopathy in Drosophila caused by mutations in Mhc. Montana, E.S., Littleton, J.T. J. Cell Biol. (2004) [Pubmed]
  2. The I-Ag7 MHC class II molecule linked to murine diabetes is a promiscuous peptide binder. Stratmann, T., Apostolopoulos, V., Mallet-Designe, V., Corper, A.L., Scott, C.A., Wilson, I.A., Kang, A.S., Teyton, L. J. Immunol. (2000) [Pubmed]
  3. Myosin I. Coluccio, L.M. Am. J. Physiol. (1997) [Pubmed]
  4. Myosin VI: cellular functions and motor properties. Buss, F., Spudich, G., Kendrick-Jones, J. Annu. Rev. Cell Dev. Biol. (2004) [Pubmed]
  5. Alteration in crossbridge kinetics caused by mutations in actin. Drummond, D.R., Peckham, M., Sparrow, J.C., White, D.C. Nature (1990) [Pubmed]
  6. Left-right asymmetry: class I myosins show the direction. Spéder, P., Noselli, S. Curr. Opin. Cell Biol. (2007) [Pubmed]
  7. Molecular mechanisms of nonmuscle myosin-II regulation. Bresnick, A.R. Curr. Opin. Cell Biol. (1999) [Pubmed]
  8. Troponin I is required for myofibrillogenesis and sarcomere formation in Drosophila flight muscle. Nongthomba, U., Clark, S., Cummins, M., Ansari, M., Stark, M., Sparrow, J.C. J. Cell. Sci. (2004) [Pubmed]
  9. Alternative s2 hinge regions of the Myosin rod differentially affect muscle function, myofibril dimensions and Myosin tail length. Suggs, J.A., Cammarato, A., Kronert, W.A., Nikkhoy, M., Dambacher, C.M., Megighian, A., Bernstein, S.I. J. Mol. Biol. (2007) [Pubmed]
  10. The expression pattern and cellular localisation of Myosin VI during the Drosophila melanogaster life cycle. Millo, H., Bownes, M. Gene Expr. Patterns (2007) [Pubmed]
  11. Transcriptional regulation of the Drosophila melanogaster muscle myosin heavy-chain gene. Hess, N.K., Singer, P.A., Trinh, K., Nikkhoy, M., Bernstein, S.I. Gene Expr. Patterns (2007) [Pubmed]
  12. Drosophila MEF2, a transcription factor that is essential for myogenesis. Bour, B.A., O'Brien, M.A., Lockwood, W.L., Goldstein, E.S., Bodmer, R., Taghert, P.H., Abmayr, S.M., Nguyen, H.T. Genes Dev. (1995) [Pubmed]
  13. Cytoplasmic myosin from Drosophila melanogaster. Kiehart, D.P., Feghali, R. J. Cell Biol. (1986) [Pubmed]
  14. Expression profiling of a hypercontraction-induced myopathy in Drosophila suggests a compensatory cytoskeletal remodeling response. Montana, E.S., Littleton, J.T. J. Biol. Chem. (2006) [Pubmed]
  15. Flightin, a novel myofibrillar protein of Drosophila stretch-activated muscles. Vigoreaux, J.O., Saide, J.D., Valgeirsdottir, K., Pardue, M.L. J. Cell Biol. (1993) [Pubmed]
  16. Factors involved in cardiogenesis and the regulation of cardiac-specific gene expression. Mably, J.D., Liew, C.C. Circ. Res. (1996) [Pubmed]
  17. Cloning of a crustacean myosin heavy chain isoform: exclusive expression in fast muscle. Cotton, J.L., Mykles, D.L. J. Exp. Zool. (1993) [Pubmed]
  18. 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]
  19. Flightin is a myosin rod binding protein. Ayer, G., Vigoreaux, J.O. Cell Biochem. Biophys. (2003) [Pubmed]
  20. Formation of reverse rigor chevrons by myosin heads. Reedy, M.C., Beall, C., Fyrberg, E. Nature (1989) [Pubmed]
  21. Spectroscopic characterization of a high-affinity calmodulin-target peptide hybrid molecule. Martin, S.R., Bayley, P.M., Brown, S.E., Porumb, T., Zhang, M., Ikura, M. Biochemistry (1996) [Pubmed]
  22. Defects in the Drosophila myosin rod permit sarcomere assembly but cause flight muscle degeneration. Kronert, W.A., O'Donnell, P.T., Fieck, A., Lawn, A., Vigoreaux, J.O., Sparrow, J.C., Bernstein, S.I. J. Mol. Biol. (1995) [Pubmed]
  23. Alterations in flightin phosphorylation in Drosophila flight muscles are associated with myofibrillar defects engendered by actin and myosin heavy-chain mutant alleles. Vigoreaux, J.O. Biochem. Genet. (1994) [Pubmed]
  24. Specific myosin heavy chain mutations suppress troponin I defects in Drosophila muscles. Kronert, W.A., Acebes, A., Ferrús, A., Bernstein, S.I. J. Cell Biol. (1999) [Pubmed]
  25. Variable N-terminal regions of muscle myosin heavy chain modulate ATPase rate and actin sliding velocity. Swank, D.M., Knowles, A.F., Kronert, W.A., Suggs, J.A., Morrill, G.E., Nikkhoy, M., Manipon, G.G., Bernstein, S.I. J. Biol. Chem. (2003) [Pubmed]
  26. An alternative domain near the ATP binding pocket of Drosophila myosin affects muscle fiber kinetics. Swank, D.M., Braddock, J., Brown, W., Lesage, H., Bernstein, S.I., Maughan, D.W. Biophys. J. (2006) [Pubmed]
  27. Drosophila nonmuscle myosin II has multiple essential roles in imaginal disc and egg chamber morphogenesis. Edwards, K.A., Kiehart, D.P. Development (1996) [Pubmed]
  28. Troponin of asynchronous flight muscle. Bullard, B., Leonard, K., Larkins, A., Butcher, G., Karlik, C., Fyrberg, E. J. Mol. Biol. (1988) [Pubmed]
  29. Functional domains of the Drosophila melanogaster muscle myosin heavy-chain gene are encoded by alternatively spliced exons. George, E.L., Ober, M.B., Emerson, C.P. Mol. Cell. Biol. (1989) [Pubmed]
  30. Coordinated cell-shape changes control epithelial movement in zebrafish and Drosophila. Köppen, M., Fernández, B.G., Carvalho, L., Jacinto, A., Heisenberg, C.P. Development (2006) [Pubmed]
  31. Multicellular rosette formation links planar cell polarity to tissue morphogenesis. Blankenship, J.T., Backovic, S.T., Sanny, J.S., Weitz, O., Zallen, J.A. Dev. Cell (2006) [Pubmed]
  32. Ifm(2)2 is a myosin heavy chain allele that disrupts myofibrillar assembly only in the indirect flight muscle of Drosophila melanogaster. Chun, M., Falkenthal, S. J. Cell Biol. (1988) [Pubmed]
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