scholarly journals Association of microinjected myosin and its subfragments with myofibrils in living muscle cells.

1988 ◽  
Vol 107 (6) ◽  
pp. 2213-2221 ◽  
Author(s):  
C S Johnson ◽  
N M McKenna ◽  
Y Wang
Keyword(s):  
Skeletal Muscle ◽  
Similar Pattern ◽  
Fluorescence Recovery After Photobleaching ◽  
Muscle Cells ◽  
Heavy Meromyosin ◽  
Ionic Condition ◽  
Skeletal Muscle Myosin ◽  
Fluorescent Heavy Meromyosin ◽  
Muscle Myosin ◽  
Low Solubility

Purified skeletal muscle myosin was labeled with iodoacetamidofluorescein and microinjected into cultured chick myotubes. The fluorescent myosin analogue became incorporated within 10-15 min after injection, into either periodic (mean periodicity = 2.23 +/- 0.02 micron) bands or apparently continuous fibrillar structures. Comparison of rhodamine-labeled alpha-actinin with coinjected fluorescein-labeled myosin suggested that myosin fluorescence was localized at the A-bands of myofibrils. In addition, close examination of the fluorescent myosin bands indicated that they were composed of two fluorescent bars separated by a nonfluorescent line that corresponded to the H-zone. Once incorporated, the myosin underwent a relatively slow exchange along myofibrils as indicated by fluorescence recovery after photobleaching. Glycerinated myofibrils were able to bind fluorescent myosin in a similar pattern in the presence or absence of MgATP, indicating that actin-myosin interactions had little effect on this process. Fluorescent heavy meromyosin did not incorporate into myofibrillar structures after injection. Light meromyosin, however, associated with A-bands as did whole myosin. These results suggest that microinjected myosin, even with its relatively low solubility under the cytoplasmic ionic condition, is capable of association with physiological structures in living muscle cells. Additionally, the light meromyosin portion of the molecule appears to be mainly responsible for the incorporation.

scholarly journals Action of Dinitrophenyl Amino Acids on Skeletal Muscle Proteins

1969 ◽  
Vol 22 (1) ◽  
pp. 205
Author(s):  
RW Burley ◽  
Jean P Robertson
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Equilibrium Dialysis ◽  
Total Absorption ◽  
Muscle Proteins ◽  
Heavy Meromyosin ◽  
Skeletal Muscle Myosin ◽  
Skeletal Muscle Proteins ◽  
Sulphydryl Groups ◽  
Muscle Myosin

Isotherms for the total absorption ofbis(2,4-dinitrophenyl)-L-lysine (bis-DNP-lysine) by rabbit skeletal muscle myosin and heavy meromyosin whose sulphydryl groups had been progressively blocked with p-chloromercuribenzoate were measured by equilibrium dialysis in Tris buffers containing potassium chloride.

scholarly journals A comparison of the effects of calponin on smooth and skeletal muscle actomyosin systems in the presence and absence of caldesmon

1992 ◽  
Vol 288 (3) ◽  
pp. 733-739 ◽  
Author(s):  
S J Winder ◽  
C Sutherland ◽  
M P Walsh
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Smooth Muscle Actin ◽  
Smooth Muscle Myosin ◽  
Muscle Actin ◽  
Heavy Meromyosin ◽  
Muscle System ◽  
Skeletal Muscle Myosin ◽  
Actomyosin Atpase ◽  
Muscle Myosin

Thiosphosphorylated smooth muscle myosin and skeletal muscle myosin, both of which express Ca(2+)-independent actin-activated MgATPase activity, were used to examine the functional effects of calponin and caldesmon separately and together. Separately, calponin and caldesmon inhibited the actin-activated MgATPase activities of thiophosphorylated smooth muscle myosin and skeletal muscle myosin, calponin being significantly more potent in both systems. Calponin-mediated inhibition resulted from the interaction of calponin with actin since it could be reversed by increasing the actin concentration. Caldesmon had no significant influence on the calponin-induced inhibition of the smooth muscle actomyosin ATPase, nor did calponin have a significant effect on caldesmon-induced inhibition. In the skeletal muscle system, however, caldesmon was found to override the inhibitory effect of calponin. This difference probably reflects the lower affinity of skeletal muscle actin for calponin compared with that of smooth muscle actin. Calponin inhibition of skeletal muscle actin-activated myosin MgATPase was not significantly affected by troponin/tropomyosin, suggesting that the thin filament can readily accommodate calponin in addition to the troponin complex, or that calponin may be able to displace troponin. Calponin also inhibited acto-phosphorylated smooth muscle heavy meromyosin and acto-skeletal muscle heavy meromyosin MgATPases. The most appropriate protein preparations for analysis of the regulatory effects of calponin in the actomyosin system therefore would be smooth muscle actin, tropomyosin and thiophosphorylated myosin, and for analysis of the kinetic effects of calponin on the actomyosin ATPase cycle they would be smooth muscle actin, tropomyosin and phosphorylated heavy meromyosin, due to the latter's solubility.

scholarly journals Electron microscopy of synthetic myosin filaments. Evidence for cross-bridge. Flexibility and copolymer formation.

1975 ◽  
Vol 67 (1) ◽  
pp. 93-104 ◽  
Author(s):  
T D Pollard
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Structural Features ◽  
Length Frequency ◽  
Single Population ◽  
Skeletal Muscle Myosin ◽  
Distinctive Features ◽  
Myosin Filaments ◽  
The Mean ◽  
Muscle Myosin

Electron micrographs of negatively stained synthetic myosin filaments reveal that surface projections, believed to be the heads of the constituent myosin molecules, can exist in two configurations. Some filaments have the projections disposed close to the filament backbone. Other filaments have all of their projections widely spread, tethered to the backbone by slender threads. Filaments formed from the myosins of skeletal muscle, smooth muscle, and platelets each have distinctive features, particularly their lengths. Soluble mixtures of skeletal muscle myosin with either smooth muscle myosin or platelet myosin were dialyzed against 0.1 M KC1 at pH 7 to determine whether the simultaneous presence of two types of myosin would influence the properties of the filaments formed. In every case, a single population of filaments formed from the mixtures. The resulting filaments are thought to be copolymers of the two types of myosin, for several reasons: (a) their length-frequency distribution is unimodal and differs from that predicted for a simple mixture of two types of myosin filaments; (b) their mean length is intermediate between the mean lengths of the filaments formed separately from the two myosins in the mixture; (c) each of the filaments has structural features characteristic of both of the myosins in the mixture; and (d) their size and shape are determined by the proportion of the two myosins in the mixture.

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