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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pectoral muscle from normal and dystrophic New Hampshire chicken embryos was dissociated and grown in vitro. Marked differences between the two types of cell cultures were observed with the light and electron microscopes during early myogenic stages. The diseased myoblasts assumed a polarized affect and fused into smaller and fewer myotubes. Pseudostraps rather than true muscle straps were often seen in diseased cultures. There was also a delay in the appearance of myosin containing thick myofilaments in differentiating dystrophic muscle cells.
Virchows Arch B Cell Pathol Incl Mol Pathol 1979
PMID:Aspects of normal and dystrophic chicken muscle grown in vitro. 4 18

Samples of normal human thymus of different ages (4-63 years old) were studied by immunofluorescence microscopy (using antibodies to smooth muscle myosin, to actin from the chicken gizzard, and antibodies to myosin from human striated muscle) as well as by routine electron microscopy. Thymus tissue from myasthenia gravis patients was also investigated for comparative reasons. Epithelial cells reacted with anti-smooth, but not with anti-striated muscle myosin, whereas myoid cells reacted with antibodies to striated, but not to smooth muscle myosin. Both epithelial and myoid cells displayed a strong immunoreactivity with antiactin. Corresponding to this immunoreactivity, both cell types contained bundles of thin, actin-like filaments. Myoid cells occurred in the rounded and elongated variety, and they were a normal constituent of all thymuses investigated in this study. Ultrastructurally, this non-innervated, striated muscle-like cell type possessed bundles of thin and thick filaments as well as Z lines in a rather disorganized arrangement, resembling striated muscle after denervation or various other pathologic conditions. There were no overt differences in the number and structure of myoid cells between healthy and myasthenic patients.
Virchows Arch B Cell Pathol Incl Mol Pathol 1979 Dec
PMID:Myosin and actin containing cells in the human postnatal thymus. Ultrastructural and immunohistochemical findings in normal thymus and in myasthenia gravis. 4 51

Immobilization of myosin, actin, actomyosin and subfragment S1 on kapron fibre was achieved with the help of glutaric aldehyde. The ATPase activity of myosin and its ability to interact with actin is preserved; while the ATPase activity of S1 subfragment decreases considerably. The immobilization on kapron fibre changes the pH-dependance of ATPase activity of myosin and that of subfragment S1, shifting the maximum to low pH zone (pH 5.5), and increases the thermostability of the enzyme. The ions of Ca++ in all cases act as an activating agent on ATPase while the ions of Mg++ either do not affect myosin and subfragment S1 at all, or increase the activity in the case of the immobilized of actomyosin but to a lesser degree than the ions of Ca++. The immobilized actin preserves its ability to form actomyosin complex.
Mol Biol (Mosk)
PMID:[Chemical suturing of myosin and actin to capron fiber]. 13 56

A method for primary culture of ovine myometrial cells is described. After dissection, myometrium of ewe uteri was digested in trypsin and collagenase. The cells were preplated for 1 h at 37 degrees C. The non-attached cells were grown in appropriate medium supplemented with 2% fetal calf serum. They had a doubling time of 3 days, reached confluency at 10 days and did not exhibit contact inhibition. Cultures were maintained up to 22 days. Characterization of the cells was achieved by electron microscopy, analysis of myosin in cell extracts and assessment of hormone sensitivity. The cells were found to contain myofilaments, characteristic of smooth muscle. A high content of myosin (6--13%) was demonstrated on SDS-polyacrylamide gel electrophoresis: this was confirmed by ATPase activity assay. Cells responded to estradiol stimulation by increased protein synthesis, and bound [3H]estradiol in a specific and saturable way. These results suggest that myometrial cells grown in primary culture should provide a useful model for studying the hormonal control of contractile protein synthesis.
Mol Cell Endocrinol 1978 Oct
PMID:Myometrial cells in primary culture: characterization and hormonal profile. 15 21

Literature data and the author's materials concerning the intermediate stages of ATP hydrolysis by myosin and actomyosin are reviewed. The scheme of hydrolytic stages based on the application of fluorescent and UV spectroscopic stop-flow and 18O exchange methods is discussed. Some unsolved problems of the hydrolytic mechanism and its relation to energy transduction in the mechanochemical act are also considered.
Mol Biol (Mosk)
PMID:[Modern views on mechanism of ATP hydrolysis by myosin (on the 40th anniversary of myosin enzymatic activity discovery)]. 15 79

The maximum parsimony method was used to reconstruct the genealogical history of the family of intracellular calcium-binding proteins represented by six major present-day lineages, three of which--calcium dependent modulator protein, heart and skeletal muscle troponin Cs, and alkali light chains of myosin--were found to share a closer kinship with one another than with the other lineages. Similarly, parvalbumins and regulatory light chains of myosin were depicted as more closely related, whereas the branch of intestinal calcium-binding protein proved to have the most distant separation. The computer-generated amino acid sequence for the common ancestor of these six lineages described a four domain protein in which each domain of approximately 40 amino acid residues had a mid-region. 12 residue segment that bound calcium and had properties most resembling those of the calcium dependent modulator protein. It could then be deduced that parvalbumins evolved by deletion of domain I, inactivation of calcium-binding properties in domain II, and acquisition of increased affinity for Ca++ and Mg++ in domains III and IV. Regulatory light chains of myosin lost the cation binding property from three domains, retaining it in I, whereas alkali light chains of myosin lost this ability from each of the four domains. In skeletal muscle troponin C all domains retained their calcium-binding activity; however, like parvalbumins, domains III and IV acquired high affinity properties. Cardiac troponin C lost its binding activity from domain I but otherwise resembled the skeletal muscle form. Finally, intestinal calcium-binding protein evolved by deletion of domains III and IV. Positive selection could be implicated in these evolutionary changes in that the rate of fixation of mutations substantially increased in the mid portions of those domains which were loosing calcium-binding activity. Likewise, when the cation binding sites were changing from low to high affinity, an accelerated rate of fixed mutations was observed. Once this new functional parameter was selected these regions showed a remarkable conservatism, as did those binding sites which were maintaining the lower affinity. Moreover even in sequence regions not directly involved in cation binding, the lineage of troponin C because very conservative over the past 300 million years, perhaps becuase of the necessity for maintaining specific interfaces in order for the molecule to interact with troponin I and T in a functional thin myofilament. A similar phenomenon was observed in domain II of the regulatory light chains of the myosin lineage suggesting a possible binding site with the heavy chain of myosin.
J Mol Evol 1979 Nov
PMID:Evolutionary diversification of structure and function in the family of intracellular calcium-binding proteins. 39 Jan 64

Two classes of myosin light chains can be distinguished functionally: those that restore calcium regulation to "desensitized" scallop myofibrils, and those that do not (Kendrick-Jones, J., et al. (1976), J. Mol. Biol. 104, 747--775). Despite this functional classification, chemical analyses reveal few patterns unique to regulatory light chains, and, indeed, sequence comparisons suggest structural similarities between both classes of myosin subunits (Collins, J. H. (1977), Nature (London) 259, 699--700; Kendrick-Jones, J., and Jakes, R. (1977), in International Symposium on Myocardial Failure at Tegernsee, Riecker, G., and Boehringer, Ed., Munich, West Germany, Springer-Verlag, pp. 28--40). Immunological assays using antisera to regulatory and to nonregulatory light chains showed no correlation between antigenic activity and the presence or absence of regulatory function. Weak cross-reactivity was observed, however, among myosin light chains and troponin C, consistent with the suggestion made on the basis of sequence homologies that these subunits contain similar structural domains (Weeds, A. G., and McLachlan, A. D. (1974), Nature (London) 252, 646--649). Unexpectedly, the strongest cross-reactivity observed was that between the vertebrate myosin alkali 1 and DTNB light chains.
 ...
PMID:Investigation of immunological relationships among myosin light chains and troponin C. 41 Apr 37

A new molecular mechanism of muscle contraction is considered based on the cyclochelate oxyphosphorane structure of the long-lived intermediate in myosin-catalyzed ATP. Mg hydrolysis proposed earlier by the author. The mechanism implies the steric cleavage of the actomyosin bond by the gamma-phosphoryl group of ATP.Mg tightly binding to myosin; the myosin-catalyzed addition of water to the gamma-phosphoryl group to give oxyphosphorane group which sterically allows the formation of a more weak bent (deformed) actomyosin bond; the actin-catalyzed breakdown of the tightly bound oxyphosphorane intermediate into weakly bound products; the straightening of the bent actomyosin bond with the active change of an angle of myosin head attachment, the liberation of the weakly bound products and the displacement of the actin filament. The data are given in favour of an oxyphosphorane structure of the long-lived intermediate.
Mol Biol (Mosk)
PMID:[Molecular mechanism of muscle contraction: the straightening of the bent actomyosin bond]. 73 89

It is shown that when myosin and heavy (HMM) and light (LMM) meromyosins are treated with concentrated solutions of neutral salts there is change in a number of parameters of the fluorescence spectra of these proteins. For myosin and HMM this change takes place in the region of the same concentrations of LiCl, MgDl2, KSCN where there occurs dissociation of the light chains of the myosin molecule. Change in the fluorescence characteristics of myosin and HMM in the presence of these salts may be caused by two effects: change in the native conformation of the myosin molecule and dissociation of its light chains. The effect of salts on LMM fluorescence is in good agreement with general theory of the influence of concentrated salts on macromolecules.
Mol Biol (Mosk)
PMID:Investigation of the fluorescence of myosin and its fragments, heavy and light meromyosins, in concentrated solutions of neutral salts. 79 56

1. Seven patients who had suffered unilateral leg fracture were studied after removal of immobilizing plaster casts. 2. Leg volume measured anthropometrically was reduced by 12% in the injured leg (5-68 +/- 1-05 litres) compared with the uninjured (6-43 +/- 0-87 litres). Associated with this loss was a similar reduction in the net maximum oxygen uptake achieved in one-leg cycling, from 1-89 +/- 0-21 1/min in the uninjured leg to 1-57 +/- 0-18 1/min in the injured. 3. Measured by a percutaneous needle biopsy technique, a reduction of 42% was found in the cross-sectional area of the muscle fibres sampled from the vastus lateralis of the injured compared with the uninjured leg. 4. Staining for myosin adenosine triphosphatase activity showed that both type I and II fibres were affected, being reduced respectively from 3410 to 1840 micronm2 and from 3810 to 2390 micronm2 cross-sectional area. 5. Possible reasons and implications are discussed for the discrepancy between the magnitude of the difference observed in the gross measurement of leg function (maximum oxygen uptake) and structure (leg volume) as compared with the cellular level (cross-sectional fibre area).
Clin Sci Mol Med 1977 Apr
PMID:Functional and structural changes after disuse of human muscle. 86 28


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