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排序方式: 共有986条查询结果,搜索用时 31 毫秒
971.
Yaroslav V. Tkachev Jinghua Ge Igor V. Negrashov Yuri E. Nesmelov 《Protein science : a publication of the Protein Society》2013,22(12):1766-1774
We have perturbed myosin nucleotide binding site with magnesium‐, manganese‐, or calcium‐nucleotide complexes, using metal cation as a probe to examine the pathways of myosin ATPase in the presence of actin. We have used transient time‐resolved FRET, myosin intrinsic fluorescence, fluorescence of pyrene labeled actin, combined with the steady state myosin ATPase activity measurements of previously characterized D.discoideum myosin construct A639C:K498C. We found that actin activation of myosin ATPase does not depend on metal cation, regardless of the cation‐specific kinetics of nucleotide binding and dissociation. The rate limiting step of myosin ATPase depends on the metal cation. The rate of the recovery stroke and the reverse recovery stroke is directly proportional to the ionic radius of the cation. The rate of nucleotide release from myosin and actomyosin, and ATP binding to actomyosin depends on the cation coordination number. 相似文献
972.
973.
974.
The contractile vacuole (CV) is a dynamic organelle that enables Dictyostelium amoeba and other protist to maintain osmotic homeostasis by expelling excess water. In the present study, we have uncovered a mechanism that coordinates the mechanics of the CV with myosin II, regulated by VwkA, an unconventional protein kinase that is conserved in an array of protozoa. Green fluorescent protein (GFP)-VwkA fusion proteins localize persistently to the CV during both filling and expulsion phases of water. In vwkA null cells, the established CV marker dajumin still localizes to the CV, but these structures are large, spherical and severely impaired for discharge. Furthermore, myosin II cortical localization and assembly are abnormal in vwkA null cells. Parallel analysis of wild-type cells treated with myosin II inhibitors or of myosin II null cells also results in enlarged CVs with impaired dynamics. We suggest that the myosin II cortical cytoskeleton, regulated by VwkA, serves a critical conserved role in the periodic contractions of the CV, as part of the osmotic protective mechanism of protozoa. 相似文献
975.
Florian Schlosser Florian Rehfeldt Christoph F. Schmidt 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2015,370(1661)
Cells are sensitive to mechanical cues from their environment and at the same time generate and transmit forces to their surroundings. To test quantitatively forces generated by cells not attached to a substrate, we used a dual optical trap to suspend 3T3 fibroblasts between two fibronectin-coated beads. In this simple geometry, we measured both the cells'' elastic properties and the force fluctuations they generate with high bandwidth. Cell stiffness decreased substantially with both myosin inhibition by blebbistatin and serum-starvation, but not with microtubule depolymerization by nocodazole. We show that cortical forces generated by non-muscle myosin II deform the cell from its rounded shape in the frequency regime from 0.1 to 10 Hz. The amplitudes of these forces were strongly reduced by blebbistatin and serum starvation, but were unaffected by depolymerization of microtubules. Force fluctuations show a spectrum that is characteristic for an elastic network activated by random sustained stresses with abrupt transitions. 相似文献
976.
977.
The effect of angiotensin II on myosin heavy chain expression in cultured myocardial cells 总被引:1,自引:0,他引:1
Noa Shalitin Menahem Friedman Hadassa Schlesinger Yael Barhum Maurice J. Levy Wolfgang Schaper Gania Kessler-Icekson 《In vitro cellular & developmental biology. Animal》1996,32(9):573-578
Summary Angiotensin II (AII), the principal mediator of the renin-angiotensin system, is an important regulator of vascular and cardiac
homeostasis. AII has also been shown to be a regulator of cardiac hypertrophy and of the corresponding changes in amount and
composition of certain tissue proteins. We examined the trophic effects of AII on cultured myocytes derived from neonatal
rat ventricles and followed, by Northern blot analysis and polyacrylamide gel electrophoresis, the expression of α- and β-myosin
heavy chain iso-mRNAs and isoproteins. Our findings show that a single administration of AII is sufficient to induce a trophic
response in cultured beating myocytes and to enhance the expression of β-myosin heavy chain iso-mRNA and isoprotein, having
no effect on α-myosin heavy chain. Induction of α-myosin heavy chain expression by thyroid hormone before AII was administered
showed that AII could not potentiate a shift from α- to β-myosin heavy chain predominance. We suggest that the potency of
AII to regulate the expression of myosin heavy chain isogenes is restricted to the β isoform and is overridden by thyroid
hormone. 相似文献
978.
979.
980.
D. S. Ushakov 《Biophysics》2008,53(6):505-509
The review summarizes the recent data on the structure and function of the essential light chain of myosin. It is known that the essential light chain of myosin stabilizes the lever arm. Consistent with the model of the shift of the dynamic population of conformations, the conformational flexibility of the essential light chain is emphasized, which opens the way to determining its new functions. It is proposed that the interaction between the C-terminal domain of the essential light chain and the N-terminal subdomain of the heavy chain of myosin may be involved in the coupling of ATP hydrolysis and rotation of the lever arm. The recent data indicate that the isoforms of the essential light chain with the additional N-terminal peptide are capable of interacting with actin and src-homologous domain 3 of myosin. The structural aspects of these interactions and the modulatory role of the isoforms of the essential light chain of myosin are discussed. 相似文献