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)

During the initial phase of myofibrillogenesis in developing muscle cells, the majority of thin filaments lie parallel to, and exhibit correct polarity and spatial position with thick filaments, as in mature myofibrils. Since myosin is known to function as an accelerator of actin polymerization in vitro, it has been postulated that myosin-actin interaction is important in the initial phase of myofibrillogenesis. To clarify further the role of actin-myosin interaction in myofibril formation during development, BDM (2, 3-butanedione 2-monoxime), an inhibitor of myosin ATPase, was applied to primary cultures of skeletal muscle to inhibit myosin activity during myofibrillogenesis, and myofibril formation was examined. When 10 mM BDM was added to the myotubes just after fusion and the cultures were maintained for a further 4 days, cross-striated myofibrils were scarcely observed by fluorescence microscopy when examined by staining with antibodies to actin, myosin, troponin and alpha-actinin, whereas in the control myotubes not exposed to BDM, typical sarcomeric structures were detected. Electron microscopy revealed a disorganized arrangement of myofilaments and incomplete sarcomeric structures in the BDM-treated myotubes. Thus, formation of cross-striated myofibrils was remarkably suppressed in the BDM-treated myotubes. When the myotubes cultured in BDM-containing media were transferred to control media, sarcomeric structures were formed in 2-3 days, suggesting that the inhibitory effect of BDM on myotubes is reversible. These results suggest that actin-myosin interaction plays a critical role in the early process of myofibrillogenesis.
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PMID:BDM (2,3-butanedione monoxime), an inhibitor of myosin-actin interaction, suppresses myofibrillogenesis in skeletal muscle cells in culture. 993 77

A depressed activity of myosin ATPase has been described in human failing myocardium. Since alterations in cross-bridge kinetics may affect both systolic and diastolic cardiac function, the present study simultaneously investigated Ca(2+)-dependent tension and actomyosin ATPase activity (MYO) in triton X-skinned fiber preparations of human non-failing (donor hearts, n=8) and failing (dilated cardiomyopathy, n=11) left ventricular myocardium at increasing sarcomeric length (1.9 and 2.1 microm, alpha-actinin staining). The MYO/tension ratio was analyzed as a parameter characterizing myofibrillar energetics. At a sarcomere length of 1.9 microm, the Ca(2+) sensitivity of tension was significantly increased in human failing compared to non-failing myocardium. In human non-failing myocardium, maximal Ca(2+)-activated tension [1.9 microm vs. 2.1 microm, 23.7 (1.9) vs. 28.3 (1.9) mN/mm(2)] and the Ca(2+) sensitivity of tension [EC(50)Ca(2+ )(pCa): 5.67 (0.06) vs. 7.07 (0.11)] were increased by increasing sarcomere length. This was accompanied by an enhancement in Ca(2+)-dependent MYO [+72 (11) vs. +101 (9) microM ADP/s] as well as an increase in the Ca(2+)-sensitivity of MYO [EC(50)Ca(2+ )(pCa): 5.84 (0.08) vs. 6.86 (0.08)]. In human failing myocardium, only Ca(2+) sensitivity of tension (but not of MYO) increased. Tension cost was increased in failing vs. non-failing tissue [1.9 microm: 4.18 (0.06) vs. 3.53 (0.06) (mN.s)/(mm(2). microM ADP); 2.1 microm: 4.28 (0.13) vs. 3.52 (0.05) (mN.s)/(mm(2). microM ADP)]. We concluded that, in human failing myocardium, the length-dependent force generation may be blunted due to an already increased Ca(2+) affinity of troponin C as well as an impairment of length-dependent cross-bridge recruitment.
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PMID:Reduced length-dependent cross-bridge recruitment in skinned fiber preparations of human failing myocardium. 1273 32

Actin filaments align around myosin filaments in the correct polarity and in a hexagonal arrangement to form cross-striated structures. It has been postulated that this myosin-actin interaction is important in the initial phase of myofibrillogenesis. It was previously demonstrated that an inhibitor of actin-myosin interaction, BDM (2,3-butanedione monoxime), suppresses myofibril formation in muscle cells in culture. However, further study showed that BDM also exerts several additional effects on living cells. In this study, we further examined the role of actin-myosin interaction in myofibril assembly in primary cultures of chick embryonic skeletal muscle by applying a more specific inhibitor, BTS (N-benzyl-p-toluene sulphonamide), of myosin ATPase and actin-myosin interaction. The assembly of sarcomeric structures from myofibrillar proteins was examined by immunocytochemical methods with the application of BTS to myotubes just after fusion. Addition of BTS (10-50 microM) significantly suppressed the organization of actin and myosin into cross-striated structures. BTS also interfered in the organization of alpha-actinin, C-protein (or MyBP-C), and connectin (or titin) into ordered striated structures, though the sensitivity was less. Moreover, when myotubes cultured in the presence of BTS were transferred to a control medium, sarcomeric structures were formed in 2-3 days, indicating that the inhibitory effect of BTS on myotubes is reversible. These results show that actin-myosin interaction plays a critical role in the process of myofibrillogenesis.
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PMID:Effects of BTS (N-benzyl-p-toluene sulphonamide), an inhibitor for myosin-actin interaction, on myofibrillogenesis in skeletal muscle cells in culture. 1718 9