The myosin alkali light chains of mouse ventricular and slow skeletal muscle are indistinguishable and are encoded by the same gene.

In order to compare the ability of different isoforms of myosin essential light chain to interact with actin, the effect of the latter protein on the proteolytic susceptibility of myosin light chains (MLC-1S and MLC-1V - slow specific and same as ventricular isoform) from slow skeletal muscle was examined. Actin protects both slow muscle essential light chain isoforms from papain digestion, similarly as observed for fast skeletal muscle myosin (Nieznanska et al., 1998, Biochim. Biophys. Acta 1383: 71). The effect of actin decreases as ionic strength rises above physiological values for both fast and slow skeletal myosin, confirming the ionic character of the actin-essential light chain interaction. To better understand the role of this interaction, we examined the effect of synthetic peptides spanning the 10-amino-acid N-terminal sequences of myosin light chain 1 from fast skeletal muscle (MLC-1F) (MLCFpep: KKDVKKPAAA), MLC-1S (MLCSpep: KKDVPVKKPA) and MLC-1V (MLCVpep: KPEPKKDDAK) on the myofibrillar ATPase of fast and slow skeletal muscle. In the presence of MLCFpep, we observed an about 19% increase, and in the presence of MLCSpep about 36% increase, in the myofibrillar ATPase activity of fast muscle. On the other hand, in myofibrillar preparations from slow skeletal muscle, MLCSpep as well as MLCVpep caused a lowering of the ATPase activity by about 36%. The above results suggest that MLCSpep induces opposite effects on ATPase activity, depending on the type of myofibrils, but not through its specific N-terminal sequence - which differs from other MLC N-terminal peptides. Our observations lead to the conclusion that the action of different isoforms of long essential light chain is similar in slow and fast skeletal muscle. However the interaction of essential light chains with actin leads to different physiological effects probably depending on the isoforms of other myofibrillar proteins.

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Evidence for distinct phosphorylatable myosin light chains in avian heart and slow skeletal muscle

Developmental Biology ◽

10.1016/0012-1606(88)90077-2 ◽

1988 ◽

Vol 125 (1) ◽

pp. 229-233 ◽

Cited By ~ 5

Author(s):

P. Lohse ◽

B. Winter ◽

V. Mouly ◽

M.Y. Fiszman ◽

H.-H. Arnold

Keyword(s):

Skeletal Muscle ◽

Light Chains ◽

Myosin Light Chains ◽

Slow Skeletal Muscle

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Effect of External Calcium and other Divalent Cations on K+ Contractures in Denervated Slow Skeletal Muscle Fibers of the Frog

Journal of Biomedical and Allied Research ◽

10.37191/mapsci-2582-4937-1(2)-009 ◽

2019 ◽

Author(s):

Leonardo Hernández

Keyword(s):

Skeletal Muscle ◽

Binding Capacity ◽

Divalent Cations ◽

Muscle Fibers ◽

Free Calcium ◽

Slow Skeletal Muscle ◽

Skeletal Muscle Fibers ◽

Free Calcium Concentration ◽

Chronic Denervation ◽

Denervated Muscles

The influence of Ca2+ and other divalent cations on contractile responses of slow skeletal muscle fibers of the frog (Rana pipiens) under conditions of chronic denervation was investigated.Isometric tension was recorded from slow bundles of normal and denervated cruralis muscle in normal solution and in solutions with free calcium concentration solution or in solutions where other divalent cations (Sr2+, Ni2+, Co2+ or Mn2+) substituted for calcium. In the second week after nerve section, in Ca2+-free solutions, we observed that contractures (evoked from 40 to 80 mM-K+) of non-denervated muscles showed significantly higher tensions (p<0.05), than those from denervated bundles. Likewise, in solutions where calcium was substituted by all divalent cations tested, with exception of Mn2+, the denervated bundles displayed lower tension than non-denervated, also in the second week of denervation. In this case, the Ca2+ substitution by Sr2+ caused the higher decrease in tension, followed by Co2+ and Ni2+, which were different to non-denervated bundles, as the lowest tension was developed by Mn2+, followed by Co2+, and then Ni2+ and Sr2+. After the third week, we observed a recovery in tension. These results suggest that denervation altering the binding capacity to divalent cations of the voltage sensor.

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Slow skeletal muscle myosin-binding protein-C (MyBPC1) mediates recruitment of muscle-type creatine kinase (CK) to myosin

Biochemical Journal ◽

10.1042/bj20102007 ◽

2011 ◽

Vol 436 (2) ◽

pp. 437-445 ◽

Cited By ~ 31

Author(s):

Zhe Chen ◽

Tong-Jin Zhao ◽

Jie Li ◽

Yan-Song Gao ◽

Fan-Guo Meng ◽

...

Keyword(s):

Skeletal Muscle ◽

Creatine Kinase ◽

Muscle Contraction ◽

Binding Protein ◽

High Energy ◽

Functional Coupling ◽

Muscle Type ◽

Myosin Binding Protein ◽

Slow Skeletal Muscle ◽

Myosin Binding

Muscle contraction requires high energy fluxes, which are supplied by MM-CK (muscle-type creatine kinase) which couples to the myofibril. However, little is known about the detailed molecular mechanisms of how MM-CK participates in and is regulated during muscle contraction. In the present study, MM-CK is found to physically interact with the slow skeletal muscle-type MyBPC1 (myosin-binding protein C1). The interaction between MyBPC1 and MM-CK depended on the creatine concentration in a dose-dependent manner, but not on ATP, ADP or phosphocreatine. The MyBPC1–CK interaction favoured acidic conditions, and the two molecules dissociated at above pH 7.5. Domain-mapping experiments indicated that MM-CK binds to the C-terminal domains of MyBPC1, which is also the binding site of myosin. The functional coupling of myosin, MyBPC1 and MM-CK is further corroborated using an ATPase activity assay in which ATP expenditure accelerates upon the association of the three proteins, and the apparent Km value of myosin is therefore reduced. The results of the present study suggest that MyBPC1 acts as an adaptor to connect the ATP consumer (myosin) and the regenerator (MM-CK) for efficient energy metabolism and homoeostasis.

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