Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.4.1 (myosin ATPase)
 1,140 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cofilin, a 21 000 molecular weight protein of porcine brain, reacts stoichiometrically with actin in a 1:1 molar ratio. Upon binding of cofilin, the fluorescence of pyrene-labeled actin under polymerizing conditions is changed into the monomer form, irrespective of whether cofilin is added to actin before or after polymerization. Cofilin decreases the viscosity of actin filaments but increases the light-scattering intensity of the filaments. The centrifugation assay and the DNase I inhibition assay demonstrate that cofilin binds to actin filaments in a 1:1 molar ratio of cofilin to actin monomer in the filament and that cofilin increases the monomeric actin to a limited extent (up to 1.1-1.5 microM monomer) in the presence of physiological concentrations of Mg2+ and KCl. Cofilin is also able to bind to monomeric actin, as demonstrated by gel filtration. Electron microscopy showed that actin filaments are shortened and slightly thickened in the presence of cofilin. No bundle formation was observed in the presence of various concentrations of cofilin. The gel point assay using an actin cross-linking protein and the nucleation assay also suggested that cofilin shortens the actin filaments and hence increases the filament number. Cofilin blocks the binding of tropomyosin to actin filaments. Tropomyosin is dissociated from actin filaments by the binding of cofilin to actin filaments. Cofilin was found to inhibit the superprecipitation of actin-myosin mixtures as well as the actin-activated myosin ATPase. All these results suggest that cofilin is a new type of actin-associated protein.
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PMID:Cofilin, a protein in porcine brain that binds to actin filaments and inhibits their interactions with myosin and tropomyosin. 650 22

Actin depolymerizing factor (ADF)/cofilin is a widely distributed family of actin-binding proteins which regulate actin polymerization in a pH-dependent manner. In cultured cells, cofilin, as well as ADF, translocates from the cytoplasm into the nucleus together with actin and forms rod-like structures in response to heat shock or dimethylsulfoxide (DMSO) treatment. In order to study in vivo interaction of cofilin with actin, we examined the effects of cofilin overexpression on actin cytoskeleton in C2 myoblasts. Interestingly, no remarkable effect was observed on phalloidin-stained patterns in cells overexpressing cofilin as compared with normal cells. However, upon treatment with DMSO, cytoplasmic actin filaments were disrupted and intranuclear rod structures containing cofilin and actin were apparently larger and thicker in cells overexpressing cofilin than in normal cells. Heat shock also stimulated disruption of microfilaments and formation of both intranuclear and prominent cytoplasmic cofilin-actin rods in cofilin-transfected cells, suggesting that DMSO-treatment or heat shock triggers cofilin-actin interaction. We further found that a myosin ATPase inhibitor (BDM) induced a reduction in cytoplasmic staining with phalloidin in cofilin-transfected cells. The results suggest that myosin activity might be involved in the regulation of cofilin-actin interactions in vivo.
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PMID:Stimulus-dependent disorganization of actin filaments induced by overexpression of cofilin in C2 myoblasts. 907 7

The cytoskeleton is widely considered essential for neurulation, yet the mouse spinal neural tube can close despite genetic and non-genetic disruption of the cytoskeleton. To investigate this apparent contradiction, we applied cytoskeletal inhibitors to mouse embryos in culture. Preventing actomyosin cross-linking, F-actin assembly or myosin II contractile activity did not disrupt spinal closure. In contrast, inhibiting Rho kinase (ROCK, for which there are two isoforms ROCK1 and ROCK2) or blocking F-actin disassembly prevented closure, with apical F-actin accumulation and adherens junction disturbance in the neuroepithelium. Cofilin-1-null embryos yielded a similar phenotype, supporting the hypothesis that there is a key role for actin turnover. Co-exposure to Blebbistatin rescued the neurulation defects caused by RhoA inhibition, whereas an inhibitor of myosin light chain kinase, ML-7, had no such effect. We conclude that regulation of RhoA, Rho kinase, LIM kinase and cofilin signalling is necessary for spinal neural tube closure through precise control of neuroepithelial actin turnover and actomyosin disassembly. In contrast, actomyosin assembly and myosin ATPase activity are not limiting for closure.
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PMID:Rho-kinase-dependent actin turnover and actomyosin disassembly are necessary for mouse spinal neural tube closure. 2604 Feb 87