Disease relevance of Tm1

• The sequence of the heavy chain complementarity-determining region 3 of K1-4c is strikingly similar to that of a monoclonal antibody (F11.2.32) specific for HIV-1 protease [1].

High impact information on Tm1

• Requirement for Drosophila cytoplasmic tropomyosin in oskar mRNA localization [2].
• In a screen for mutants defective in germ cell formation, we isolated nine alleles of the tropomyosin II gene [2].
• Normal Drosophila have a fractional shortening of 87 +/- 4%, whereas cardiomyopathic flies that contain a mutation in troponin I or tropomyosin show severe impairment of systolic function [3].
• One of these modifiers, Tm2, encodes tropomyosin, another component of the Tc-Tm complex [4].
• An enhancer-blocking element (BEAD-1, for blocking element alpha/delta 1) was localized to a 2.0-kb region 3' of TCR delta gene segments and 5' of TCR alpha joining gene segments within this locus [5].

Biological context of Tm1

• Interestingly, in Apis mellifera (hymenopteran), while most of the Tm1 and Tm2 gene features are conserved, the gene lacks any C-terminal exons [6].
• Lack of Drosophila cytoskeletal tropomyosin affects head morphogenesis and the accumulation of oskar mRNA required for germ cell formation [7].
• A combination of developmentally regulated promoters and alternative splicing produces both muscle and cytoskeletal tropomyosin isoforms [8].
• We report here the isolation and DNA sequence of a cDNA clone encoding a 252-amino acid non-muscle or cytoskeletal tropomyosin (cTm) isoform from Drosophila [9].
• The effects of promoter deletions on Drosophila tropomyosin I (TmI) gene expression have been determined by measuring TmI RNA levels in transformed flies [10].

Anatomical context of Tm1

• A modified protocol for the purification of vertebrate cytoplasmic tropomyosin was used to partially purify cytoplasmic tropomyosin from the Drosophila Kc cell line [11].
• (2) One cell is selected to become the oocyte and protrudes into the posterior follicle cell layer when the cyst rounds up on entering region 3 [12].

Associations of Tm1 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 two Drosophila TnHs (isoforms 33 and 34) are naturally occurring fusion proteins in which a proline-rich extension of approximately 250 amino acids replaces the 27 C-terminal residues of the muscle-specific tropomyosin II isoform [13].
• The Kc cell cytoplasmic tropomyosin comigrates in two dimensions with the hybrid-selected in vitro translation product of the region 3 gene, and both proteins show a mobility shift in NaDodSO4/urea/polyacrylamide gels that is characteristic of vertebrate tropomyosins [11].
• Identification of tropomyosin as the major shrimp allergen and characterization of its IgE-binding epitopes [14].
• The total sequence predicts a protein of 576 amino acids with three conserved regions: a 90-amino-acid repeat domain, a SH3 (src homology region 3) motif, and a guanylate kinase domain [15].

Physical interactions of Tm1

• Furthermore, we show that TmII genetically interacted with flamingo, a gene encoding a membrane receptor-like molecule that affects dendritic growth [16].

Other interactions of Tm1

• Three adjacent areas of binding by nuclear proteins from activated hepatic stellate cells were identified at -568 to -554 (region 1), -542 to -518 (region 2), and -473 to -453 (region 3) of the promoter using DNase I protection analyses [17].

Analytical, diagnostic and therapeutic context of Tm1

• Site-directed mutagenesis of a residue in transmembrane region 3 and the loop between transmembrane regions 6 and 7 affect ligand binding, as previously described for somatostatin receptors [18].
• Tryptic maps of both Sa-II and tropomyosin as obtained by reverse phase HPLC were superimposable [14].
• Shrimp tropomyosin bound to specific IgE antibodies in the sera of shrimp-sensitive patients as assessed by competitive ELISA inhibition and Western blot analysis [14].

References