High impact information on Prm

• The predicted protein contains several extended amphipathic helices, and its similarity to myosin heavy chain tails, paramyosin, and kinesin suggests a similar type of coiled-coil protein interaction [1].
• Disruption of the dADAR gene results in totally unedited sodium (Para), calcium (Dmca1A), and chloride (DrosGluCl-alpha) channels, a very prolonged recovery from anoxic stupor, a vulnerability to heat shock and increased O2 demands, and neuronal degeneration in aged flies [2].
• Drosophila paramyosin is important for myoblast fusion and essential for myofibril formation [3].
• We conclude that paramyosin plays an unexpected role in myoblast fusion and is important for myofibril assembly and muscle contraction [4].
• We confirmed that these defects are paramyosin-specific by rescuing the homozygous paramyosin mutant to adulthood with a paramyosin transgene [4].

Biological context of Prm

• One group (hinge-switch mutants) had a portion of the endogenous S2 hinge region replaced by an embryonic version; the other group (paramyosin mutants) had one or more putative phosphorylation sites near the N-terminus of paramyosin disabled [5].
• Antibody analysis of normal embryos demonstrated that paramyosin accumulates as a cytoplasmic protein in early embryo development before assembling into thick filaments [4].
• The expression of miniparamyosin is controlled by two enhancers, AB and TX, but a BF modulator is required to ensure the correct levels of expression in each particular muscle [6].
• Several cDNA clones encoding the complete Drosophila paramyosin sequence, including two potential polyadenylation sites, have been obtained [7].
• Southern analysis and in situ hybridization to polytene chromosomes indicate that in Drosophila the paramyosin gene is single copy, located on the left arm of the third chromosome at region 66D14 [7].

Anatomical context of Prm

• In contrast, the mechanical defects observed upon disrupting paramyosin phosphorylation sites in Drosophila suggests that paramyosin phosphorylation is important for maintaining high passive stiffness in IFM myofibrils, probably by affecting paramyosin's interaction with other sarcomeric proteins [5].
• Drosophila paramyosin is important for myoblast fusion and essential for myofibril formation [4].
• Freshly prepared tubular myofibrils decorated with the immunoabsorbed antibody show the A region in the sarcomere as the specific localization of paramyosin [8].
• Analysis of Lqhbeta1 effects on rat brain and Drosophila Para NaChs expressed in Xenopus oocytes revealed a shift in the voltage-dependence of activation to more negative membrane potentials and a reduction in sodium peak currents in a manner typifying beta-toxin activity [9].
• The presence and distribution pattern of paramyosin have been examined in different invertebrate muscle cell types by means of Western blot analysis and electron microscopy immunogold labelling [10].

Associations of Prm with chemical compounds

• To investigate the importance of paramyosin phosphorylation, we produced transgenic Drosophila melanogaster in which one, three, or four phosphorylatable serine residues in the N-terminal nonhelical domain were replaced by alanines [11].

Analytical, diagnostic and therapeutic context of Prm

• Two-dimensional and one-dimensional Western blot analyses have revealed that miniparamyosin has several isoforms, focusing over a very wide pH range, all of which are phosphorylated in vivo [12].
• Immunofluorescence and EM data indicate that miniparamyosin is mainly located in the M line and at both ends of the thick filaments in Drosophila indirect flight muscles, while paramyosin is present all along the thick filaments [12].

References