The binding of actin to phosphorylated and dephosphorylated myosin

Michnicka, Malgorzata; Kasman, Krystyna; Kakol, I

doi:10.1016/0167-4838(82)90069-3

Cited by 21 publications

(10 citation statements)

References 23 publications

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“…In other words, BDM and RLC phosphorylation operate on the same step in the crossbridge cycle, namely, P i release, but in opposing directions. This notion is consistent with their opposite effects on the rate of crossbridge attachment (4,38,61), the affinity of myosin for actin (37,39) and the diffraction changes reported here. Since blebbistatin blocks P i release in the same way as BDM does, it is likely that RLC phosphorylation would also oppose the inhibitory action of blebbistatin on tetanic tension as BDM does (11).…”

Section: Discussionsupporting

confidence: 91%

“…There exists biochemical and biophysical evidence pointing to the existence of direct effects of RLC phosphorylation on the interaction between actin and myosin even when extracted from the filament lattice. The affinity of phosphorylated myosin for actin is about twofold higher than that for dephosphorylated myosin (39,44,46). This is in sharp contrast to the weakening of this affinity by BDM (37).…”

Section: Discussionmentioning

confidence: 83%

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X-ray diffraction analysis of the effects of myosin regulatory light chain phosphorylation and butanedione monoxime on skinned skeletal muscle fibers

Yamaguchi

Kimura

et al. 2016

American Journal of Physiology-Cell Physiology

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The phosphorylation of the myosin regulatory light chain (RLC) is an important modulator of skeletal muscle performance and plays a key role in posttetanic potentiation and staircase potentiation of twitch contractions. The structural basis for these phenomena within the filament lattice has not been thoroughly investigated. Using a synchrotron radiation source at SPring8, we obtained X-ray diffraction patterns from skinned rabbit psoas muscle fibers before and after phosphorylation of myosin RLC in the presence of myosin light chain kinase, calmodulin, and calcium at a concentration below the threshold for tension development ([Ca(2+)] = 10(-6.8)M). After phosphorylation, the first myosin layer line slightly decreased in intensity at ∼0.05 nm(-1)along the equatorial axis, indicating a partial loss of the helical order of myosin heads along the thick filament. Concomitantly, the (1,1/1,0) intensity ratio of the equatorial reflections increased. These results provide a firm structural basis for the hypothesis that phosphorylation of myosin RLC caused the myosin heads to move away from the thick filaments towards the thin filaments, thereby enhancing the probability of interaction with actin. In contrast, 2,3-butanedione monoxime (BDM), known to inhibit contraction by impeding phosphate release from myosin, had exactly the opposite effects on meridional and equatorial reflections to those of phosphorylation. We hypothesize that these antagonistic effects are due to the acceleration of phosphate release from myosin by phosphorylation and its inhibition by BDM, the consequent shifts in crossbridge equilibria leading to opposite changes in abundance of the myosin-ADP-inorganic phosphate complex state associated with helical order of thick filaments.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 83%

X-ray diffraction analysis of the effects of myosin regulatory light chain phosphorylation and butanedione monoxime on skinned skeletal muscle fibers

Yamaguchi

Kimura

et al. 2016

American Journal of Physiology-Cell Physiology

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“…Further study demonstrates that the ATPase activity of myosin from rabbit fast‐twitch skeletal muscle is not significantly changed by MRLC phosphorylation (Morgan et al ., ). Some other studies report that the actomyosin ATPase activity was higher when the MRLC is in dephosphorylated form when it is determined under conditions similar to physiological (Kakol et al ., ; Michnicka et al ., ), which is in agreement with our result. In our experiment, it showed that the phosphorylation level of MRLC decreased gradually following the incubation time in the control and AP groups, but in the phosphatase inhibitor group, it gradually decreased after a stable period, while the actomyosin ATPase activity presented a slowly decrease after a gradual increase in the three groups.…”

Section: Discussionsupporting

confidence: 94%

Dephosphorylation of myosin regulatory light chain modulates actin–myosin interaction adverse to meat tenderness

Gao

et al. 2017

Int J of Food Sci Tech

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The objective of this study was to investigate the relationship between the dephosphorylation of myosin regulatory light chain and actin-myosin interaction after muscle homogenate was treated with alkaline phosphatase and phosphatase inhibitor. The myosin regulatory light chain was significantly dephosphorylated by alkaline phosphatase after incubation. Among different groups, dephosphorylated myosin regulatory light chain to a much greater extent leads to a lower actomyosin dissociation degree, thereby raising the actomyosin ATPase activity, whereas it exhibits a higher actomyosin dissociation degree and a lower actomyosin ATPase activity when the myosin regulatory light chain was in a low dephosphorylated state. The data suggest that the dephosphorylation of myosin regulatory light chain modulates actomyosin dissociation (the number of myosin interact with actin) negatively and has a positive influence on actomyosin ATPase activity (the interacting force between myosin and actin).Dephosphorylation modulates actinmyosin X. Gao et al.

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“…Rabbit skeletal myosin was obtained as described earlier (26,41). F-actin, Tm, and Tn were isolated and purified from rabbit skeletal muscle according to Strzelecka-Golaszewska et al (42), Potter (33), and Smillie (40), respectively.…”

Section: Actin-activated Atpase Assaysmentioning

confidence: 99%

Phosphorylation of the regulatory light chains of myosin affects Ca²⁺sensitivity of skeletal muscle contraction

Szczêsna

Zhao

Jones

et al. 2002

Journal of Applied Physiology

106

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The role of phosphorylation of the myosin regulatory light chains (RLC) is well established in smooth muscle contraction, but in striated (skeletal and cardiac) muscle its role is still controversial. We have studied the effects of RLC phosphorylation in reconstituted myosin and in skinned skeletal muscle fibers where Ca2+ sensitivity and the kinetics of steady-state force development were measured. Skeletal muscle myosin reconstituted with phosphorylated RLC produced a much higher Ca2+ sensitivity of thin filament-regulated ATPase activity than nonphosphorylated RLC (change in -log of the Ca2+ concentration producing half-maximal activation = approximately 0.25). The same was true for the Ca2+ sensitivity of force in skinned skeletal muscle fibers, which increased on reconstitution of the fibers with the phosphorylated RLC. In addition, we have shown that the level of endogenous RLC phosphorylation is a crucial determinant of the Ca2+ sensitivity of force development. Studies of the effects of RLC phosphorylation on the kinetics of force activation with the caged Ca2+, DM-nitrophen, showed a slight increase in the rates of force development with low statistical significance. However, an increase from 69 to 84% of the initial steady-state force was observed when nonphosphorylated RLC-reconstituted fibers were subsequently phosphorylated with exogenous myosin light chain kinase. In conclusion, our results suggest that, although Ca2+ binding to the troponin-tropomyosin complex is the primary regulator of skeletal muscle contraction, RLC play an important modulatory role in this process.

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The binding of actin to phosphorylated and dephosphorylated myosin

Cited by 21 publications

References 23 publications

X-ray diffraction analysis of the effects of myosin regulatory light chain phosphorylation and butanedione monoxime on skinned skeletal muscle fibers

X-ray diffraction analysis of the effects of myosin regulatory light chain phosphorylation and butanedione monoxime on skinned skeletal muscle fibers

Dephosphorylation of myosin regulatory light chain modulates actin–myosin interaction adverse to meat tenderness

Phosphorylation of the regulatory light chains of myosin affects Ca²⁺sensitivity of skeletal muscle contraction

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The binding of actin to phosphorylated and dephosphorylated myosin

Cited by 21 publications

References 23 publications

X-ray diffraction analysis of the effects of myosin regulatory light chain phosphorylation and butanedione monoxime on skinned skeletal muscle fibers

X-ray diffraction analysis of the effects of myosin regulatory light chain phosphorylation and butanedione monoxime on skinned skeletal muscle fibers

Dephosphorylation of myosin regulatory light chain modulates actin–myosin interaction adverse to meat tenderness

Phosphorylation of the regulatory light chains of myosin affects Ca2+sensitivity of skeletal muscle contraction

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Phosphorylation of the regulatory light chains of myosin affects Ca²⁺sensitivity of skeletal muscle contraction