Two Drosophila melanogaster tropomyosin genes: structural and functional aspects.

Karlik, C C; Fyrberg, Eric

doi:10.1128/mcb.6.6.1965

Cited by 111 publications

(62 citation statements)

References 21 publications

(29 reference statements)

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“…It suppresses all the effects of hdp 2 on muscle function, consistent with D53 being a mutation in constitutively expressed exon 2, and Tm2 expression occurring in the IFMs, TDT, leg muscles and supercontractile larval muscles (Basi et al, 1984;Basi and Storti, 1986;Karlik and Fyrberg, 1986).…”

Section: Discussionmentioning

confidence: 92%

“…Larval muscles express a Tm2 mRNA, containing exons 1-4; IFM and leg muscles express a Tm2 mRNA consisting of exons 1-3 and 5 (Basi et al, 1986;Karlik and Fyrberg, 1986). As D53 suppresses hdp 2 effects in IFMs, legs, and larval muscles (see below), the common coding exons (2 and 3) were sequenced by PCR of genomic DNA from hdp 2 and hdp 2 ; D53 flies.…”

Section: Suppressor D53 Is a Tropomyosin 2 Mutationmentioning

confidence: 99%

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A Tropomyosin-2 Mutation Suppresses a Troponin I Myopathy inDrosophila

Naïmi

Harrison

Cummins

et al. 2001

MBoC

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A suppressor mutation, D53, of the held-up 2 allele of the Drosophila melanogaster Troponin I (wupA) gene is described. 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. The suppressor restores normal function of the IFMs, but flight ability decreases with age and correlates with an unusual, progressive structural collapse of the myofibrillar lattice starting at the center. The S185F substitution in Tm2 is close to a troponin T binding site on tropomyosin. Models to explain suppression by D53, derived from current knowledge of the vertebrate troponin-tropomyosin complex structure and functions, are discussed. The effects of S185F are compared with those of two mutations in residues 175 and 180 of human ␣-tropomyosin 1 which cause familial hypertrophic cardiomyopathy (HCM).

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Section: Discussionmentioning

confidence: 92%

Section: Suppressor D53 Is a Tropomyosin 2 Mutationmentioning

confidence: 99%

A Tropomyosin-2 Mutation Suppresses a Troponin I Myopathy inDrosophila

Naïmi

Harrison

Cummins

et al. 2001

MBoC

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“…Stretch as well as Ca 21 is required to activate IFM muscle contraction (Peckham et al 1990;Agianian et al 2004). IFM contain homologs of most major thin filament proteins, but the IFM express different isoforms, probably to cope with their different functional demands (Fyrberg et al 1983;Karlik and Fyrberg 1986;Vigoreaux 2001;Qiu et al 2003;Herranz et al 2004;Nongthomba et al 2004). These isoforms are generated through expression of different structural genes or intragenically by use of alternative promoters or alternative transcript splicing (for review, see Bernstein et al 1993).…”

Section: Discussionmentioning

confidence: 99%

Aberrant Splicing of an Alternative Exon in the Drosophila Troponin-T Gene Affects Flight Muscle Development

et al. 2007

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During myofibrillogenesis, many muscle structural proteins assemble to form the highly ordered contractile sarcomere. Mutations in these proteins can lead to dysfunctional muscle and various myopathies. We have analyzed the Drosophila melanogaster troponin T (TnT) up 1 mutant that specifically affects the indirect flight muscles (IFM) to explore troponin function during myofibrillogenesis. The up 1 muscles lack normal sarcomeres and contain ''zebra bodies,'' a phenotypic feature of human nemaline myopathies. We show that the up 1 mutation causes defective splicing of a newly identified alternative TnT exon (10a) that encodes part of the TnT C terminus. This exon is used to generate a TnT isoform specific to the IFM and jump muscles, which during IFM development replaces the exon 10b isoform. Functional differences between the 10a and 10b TnT isoforms may be due to different potential phosphorylation sites, none of which correspond to known phosphorylation sites in human cardiac TnT. The absence of TnT mRNA in up 1 IFM reduces mRNA levels of an IFM-specific troponin I (TnI) isoform, but not actin, tropomyosin, or troponin C, suggesting a mechanism controlling expression of TnT and TnI genes may exist that must be examined in the context of human myopathies caused by mutations of these thin filament proteins.

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“…Generation of protein diversity by alternative RNA processing has been reported for genes encoding other cytoskeletal proteins including myosin light chain (27,67,73,75), troponin T (9,17,63), myosin heavy chain (79), and tropomyosin (3,43,44,53,80). In addition, alternative RNA processing for the generation of contractile protein diversity appears to be a fundamental mechanism conserved throughout evolution since it has been characterized in various species including drosophila, chickens, rats, and humans.…”

Section: Beta-tropomyosin and Fibroblast Tropomyosin 1 Cdnas Wementioning

confidence: 99%

Nonmuscle and muscle tropomyosin isoforms are expressed from a single gene by alternative RNA splicing and polyadenylation.

Helfman¹,

Cheley²,

Kuismanen³

et al. 1986

Mol. Cell. Biol.

175

122

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The molecular basis for the expression of rat embryonic fibroblast tropomyosin 1 and skeletal muscle beta-tropomyosin was determined. cDNA clones encoding these tropomyosin isoforms exhibit complete identity except for two carboxy-proximal regions (amino acids 189 to 213 and 258 to 284) and different 3'-untranslated sequences. The isoform-specific regions delineate the troponin T-binding domains of skeletal muscle tropomyosin. Analysis of genomic clones indicates that there are two separate loci in the rat genome that contain sequences complementary to these mRNAs. One locus is a pseudogene. The other locus contains a single gene made up of 11 exons and spans approximately 10 kilobases. Sequences common to all mRNAs were found in exons 1 through 5 (amino acids 1 to 188) and exons 8 and 9 (amino acids 214 to 257). Exons 6 and 11 are specific for fibroblast mRNA (amino acids 189 to 213 and 258 to 284, respectively), while exons 7 and 10 are specific for skeletal muscle mRNA (amino acids 189 to 213 and 258 to 284, respectively). In addition, exons 10 and 11 each contain the entire 3'-untranslated sequences of the respective mRNAs including the polyadenylation site. Although the gene is also expressed in smooth muscle (stomach, uterus, and vas deferens), only the fibroblast-type splice products can be detected in these tissues. S1 and primer extension analyses indicate that all mRNAs expressed from this gene are transcribed from a single promoter. The promoter was found to contain G-C-rich sequences, a TATA-like sequence TTTTA, no identifiable CCAAT box, and two putative Sp1-binding sites.

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Two Drosophila melanogaster tropomyosin genes: structural and functional aspects.

Cited by 111 publications

References 21 publications

A Tropomyosin-2 Mutation Suppresses a Troponin I Myopathy inDrosophila

A Tropomyosin-2 Mutation Suppresses a Troponin I Myopathy inDrosophila

Aberrant Splicing of an Alternative Exon in the Drosophila Troponin-T Gene Affects Flight Muscle Development

Nonmuscle and muscle tropomyosin isoforms are expressed from a single gene by alternative RNA splicing and polyadenylation.

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