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.

scholarly journals Assembly of smooth muscle myosin into side-polar filaments.

1977 ◽  
Vol 75 (3) ◽  
pp. 990-996 ◽  
Author(s):  
R Craig ◽  
J Megerman
Keyword(s):  
Smooth Muscle ◽  
Opposite Polarity ◽  
Skeletal Muscle Myosin ◽  
Myosin Filaments ◽  
Skeletal Myosin ◽  
Cross Bridges ◽  
Bipolar Filament ◽  
Muscle Myosin

The in vitro assembly of myosin purified from calf aorta muscle has been studied by electron microscopy. Two types of filament are formed: short bipolar filament similar to those formed from skeletal muscle myosin, and longer "side-polar" filaments having cross bridges with a single polarity along the entire length of one side and the opposite polarity along the other side. Unlike the case with skeletal myosin filaments, antiparallel interactions between myosin molecules occur along the whole length of side-polar filaments. The side-polar structure may be related to the in vivo form of myosin in vertebrate smooth muscle.

scholarly journals Light chain phosphorylation regulates the movement of smooth muscle myosin on actin filaments.

1985 ◽  
Vol 101 (5) ◽  
pp. 1897-1902 ◽  
Author(s):  
J R Sellers ◽  
J A Spudich ◽  
M P Sheetz
Keyword(s):  
Smooth Muscle ◽  
Actin Filaments ◽  
Smooth Muscles ◽  
Smooth Muscle Myosin ◽  
Vitro Assay ◽  
Skeletal Muscle Myosin ◽  
Myosin Filaments ◽  
Muscle Myosin ◽  
Rate Of Movement

In smooth muscles there is no organized sarcomere structure wherein the relative movement of myosin filaments and actin filaments has been documented during contraction. Using the recently developed in vitro assay for myosin-coated bead movement (Sheetz, M.P., and J.A. Spudich, 1983, Nature (Lond.)., 303:31-35), we were able to quantitate the rate of movement of both phosphorylated and unphosphorylated smooth muscle myosin on ordered actin filaments derived from the giant alga, Nitella. We found that movement of turkey gizzard smooth muscle myosin on actin filaments depended upon the phosphorylation of the 20-kD myosin light chains. About 95% of the beads coated with phosphorylated myosin moved at velocities between 0.15 and 0.4 micron/s, depending upon the preparation. With unphosphorylated myosin, only 3% of the beads moved and then at a velocity of only approximately 0.01-0.04 micron/s. The effects of phosphorylation were fully reversible after dephosphorylation with a phosphatase prepared from smooth muscle. Analysis of the velocity of movement as a function of phosphorylation level indicated that phosphorylation of both heads of a myosin molecule was required for movement and that unphosphorylated myosin appears to decrease the rate of movement of phosphorylated myosin. Mixing of phosphorylated smooth muscle myosin with skeletal muscle myosin which moves at 2 microns/s resulted in a decreased rate of bead movement, suggesting that the more slowly cycling smooth muscle myosin is primarily determining the velocity of movement in such mixtures.

Proteins of the contractile mechanism of mammalian smooth muscle and their possible location in the cell

1964 ◽  
Vol 160 (981) ◽  
pp. 517-524 ◽  
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Sedimentation Rate ◽  
Striated Muscle ◽  
Muscle Actin ◽  
Trypsin Treatment ◽  
Skeletal Muscle Myosin ◽  
Uterine Smooth Muscle ◽  
Muscle Myosin ◽  
Viscous Behaviour

Dorothy M. Needham speaking. Since the pioneer work of Csapo and his colleagues, beginning about fifteen years ago, it has been realized that from uterine smooth muscle can be extracted a protein closely resembling skeletal-muscle actomyosin in its viscous behaviour, sedimentation rate and electrophoretic mobility. (See, for example, Csapo 1948, 1949, 1950, 1959; Csapo, Erdos, Naeslund & Snellman 1950; Naeslund & Snellman 1951). Later work, in which the properties of purified preparations of myosin, actin and actomyosin have been studied, bears out these earlier conclusions. Thus, for example, we have shown (Needham & Williams 1963 b ) that skeletal-muscle myosin will react normally with uterus actin to give the highly viscous actomyosin; and similarly uterus myosin with skeletal-muscle actin. In both types of experiment the results indicated that the two proteins associated together in about the same proportions as when both are derived from skeletal muscle. Uterus actomyosin may be fragmented by carefully controlled trypsin treatment giving light and heavy meromyosins which, so far as they have been studied, show similar properties to the meromyosins from skeletal-muscle actomyosin (Needham & Williams 1959; Cohen, Lowey & Kucera 1961). Smooth muscle, however, does contain very strikingly less actomyosin than striated muscle, only 6 to 10 mg/g wet wt as compared with about 70 mg/g wet wt in skeletal muscle (Needham & Williams 1963 a ).

scholarly journals Order-disorder structural transitions in synthetic filaments of fast and slow skeletal muscle myosins under relaxing and activating conditions.

2000 ◽  
Vol 47 (4) ◽  
pp. 1007-1017 ◽  
Author(s):  
Z A Podlubnaya ◽  
S L Malyshev ◽  
K Nieznański ◽  
D Stepkowski
Keyword(s):  
Skeletal Muscle ◽  
Ordered Structure ◽  
Structural Transitions ◽  
Fast Skeletal Muscle ◽  
Skeletal Muscle Myosin ◽  
Slow Skeletal Muscle ◽  
Random Arrangement ◽  
Vertebrate Muscle ◽  
Myosin Filaments ◽  
Muscle Myosin

In the previous study (Podlubnaya et al., 1999, J. Struc. Biol. 127, 1-15) Ca2+-induced reversible structural transitions in synthetic filaments of pure fast skeletal and cardiac muscle myosins were observed under rigor conditions (-Ca2+/+Ca2+). In the present work these studies have been extended to new more order-producing conditions (presence of ATP in the absence of Ca2+) aimed at arresting the relaxed structure in synthetic filaments of both fast and slow skeletal muscle myosin. Filaments were formed from column-purified myosins (rabbit fast skeletal muscle and rabbit slow skeletal semimebranosusproprius muscle). In the presence of 0.1 mM free Ca2+, 3 mM Mg2+ and 2 mM ATP (activating conditions) these filaments had a spread structure with a random arrangement of myosin heads and subfragments 2 protruding from the filament backbone. Such a structure is indistinguishable from the filament structures observed previously for fast skeletal, cardiac (see reference cited above) and smooth (Podlubnaya et al., 1999, J. Muscle Res. Cell Motil. 20, 547-554) muscle myosins in the presence of 0.1 mM free Ca2+. In the absence of Ca2+ and in the presence of ATP (relaxing conditions) the filaments of both studied myosins revealed a compact ordered structure. The fast skeletal muscle myosin filaments exhibited an axial periodicity of about 14.5 nm and which was much more pronounced than under rigor conditions in the absence of Ca2+ (see the first reference cited). The slow skeletal muscle myosin filaments differ slightly in their appearance from those of fast muscle as they exhibit mainly an axial repeat of about 43 nm while the 14.5 nm repeat is visible only in some regions. This may be a result of a slightly different structural properties of slow skeletal muscle myosin. We conclude that, like other filaments of vertebrate myosins, slow skeletal muscle myosin filaments also undergo the Ca2+-induced structural order-disorder transitions. It is very likely that all vertebrate muscle myosins possess such a property.

scholarly journals Assembly of smooth muscle myosin minifilaments: effects of phosphorylation and nucleotide binding.

1987 ◽  
Vol 105 (6) ◽  
pp. 3007-3019 ◽  
Author(s):  
K M Trybus ◽  
S Lowey
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Conformational Changes ◽  
Myosin Head ◽  
Smooth Muscle Myosin ◽  
Detectable Effect ◽  
Skeletal Muscle Myosin ◽  
Polar Type ◽  
Low Ionic Strength ◽  
Muscle Myosin

Small bipolar filaments, or "minifilaments," are formed when smooth muscle myosin is dialyzed against low ionic strength pyrophosphate or citrate/Tris buffers. Unlike synthetic filaments formed at approximately physiological ionic conditions, minifilaments are homogeneous as indicated by their hypersharp boundary during sedimentation velocity. Electron microscopy and hydrodynamic techniques were used to show that 20-22S smooth muscle myosin minifilaments are 380 nm long and composed of 12-14 molecules. By varying solvents, a continuum of different size polymers in the range of 15-30S could be obtained. Skeletal muscle myosin, in contrast, preferentially forms a stable 32S minifilament (Reisler, E., P. Cheung, and N. Borochov. 1986. Biophys. J. 49:335-342), suggesting underlying differences in the assembly properties of the two myosins. Addition of salt to the smooth muscle myosin minifilaments caused unidirectional growth into a longer "side-polar" type of filament, whereas bipolar filaments were consistently formed by skeletal muscle myosin. As with synthetic filaments, addition of 1 mM MgATP caused dephosphorylated minifilaments to dissociate to a mixture of folded monomers and dimers. Phosphorylation of the regulatory light chain prevented disassembly by nucleotide, even though it had no detectable effect on the structure of the minifilament. These results suggest that differences in filament stability as a result of phosphorylation are due largely to conformational changes occurring in the myosin head, and are not due to differences in filament packing.

scholarly journals Force Produced by Smooth and Skeletal Muscle Myosin Filaments Measured with Micro-Fabricated Cantilevers

2018 ◽  
Vol 114 (3) ◽  
pp. 320a
Author(s):  
Yu-Shu Cheng ◽  
Md Rezuanul ◽  
Haque Saikat ◽  
Dilson Rassier
Keyword(s):  
Skeletal Muscle ◽  
Skeletal Muscle Myosin ◽  
Myosin Filaments ◽  
Muscle Myosin

IV. The mechanism of contraction - Introductory remarks

1973 ◽  
Vol 265 (867) ◽  
pp. 167-167
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Atpase Activity ◽  
Soluble Proteins ◽  
Smooth Muscle Myosin ◽  
Trypsin Treatment ◽  
Skeletal Muscle Myosin ◽  
Muscle Myosin

Our programme this afternoon is in two parts. We first welcome Professor Hamoir and Dr Kendrick-Jones to describe the several ways in which smooth muscle myosin differs from skeletal muscle myosin. It was in this biochemical field that my own work, with Dr Jennifer Williams, lay some twelve years ago. We were impressed at that time by the very low ATPase activity of the uterus actomyosin, and by the fact that on trypsin treatment meromyosins were obtained in some ways similar to those of skeletal muscle. Speakers this afternoon will have far more to tell us of the nature, behaviour and structure of the myosins concerned. We were also interested in the properties and possible function of certain soluble proteins, including tropomyosin, which figure so largely in smooth muscle constitution. This subject also will come up today.

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.

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