Calcium desensitization in cardiac troponin C: a novel role in mouse skeletal muscle

Novello, Matthew J.; Zhang, MengQi; Snyder, Hannah E.; Lin, Qi-Tong

doi:10.1113/jp277616

Cited by 1 publication

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References 5 publications

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“…Under physiological conditions, the sites III and IV are constantly occupied by Mg 2+ ions. Ca 2+ binding to the sites I and II leads to the exposure of the hydrophobic pocket of the N-lobe, which binds to the TnI switch peptide and shifts the TnI inhibitory peptide away from the actin filament, thereby allowing Tm to expose the myosin-binding sites on actin (Novello et al, 2019;Zot & Potter, 1987). Unlike sTnC, vertebrate cardiac TnC can only bind three Ca 2+ ions at sites II, III and IV, among which site II is regulatory (van Eerd & Takahashi, 1975).…”

Section: Introductionmentioning

confidence: 99%

Locusta migratoria flight muscle troponin partially activates thin filament in a calcium‐dependent manner

Liang

2022

Insect Molecular Biology

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The troponin (Tn) complex, the sensor for Ca2+ to regulate contraction of striated muscle, is composed of three subunits, that is, TnT, TnI and TnC. Different isoforms of TnI and TnC are expressed in the thorax dorsal longitudinal muscle (flight muscle) and the hind leg extensor tibiae muscle (jump muscle) of the migratory locust, Locusta migratoria. The major Tn complexes in the flight muscle and the jump muscle are Tn‐171 (TnT1/TnI7/TnC1) and Tn‐153 (TnT1/TnI5/TnC3), respectively. Here, we prepared a number of recombinant Tn complexes and the reconstituted thin filaments, and investigated their regulation on thin filament. Although both Tn‐171 and Tn‐153 regulate thin filament in a Ca2+‐dependent manner, the extent of Ca2+ activation mediated by Tn‐171 was significantly lower than that by Tn‐153. We demonstrated that TnC1 and TnC3, rather than TnI5 and TnI7, are responsible for the different levels of the thin filament activation. Mutagenesis of TnC1 and TnC3 shows that the low level of TnC1‐mediated thin filament activation can be attributed to the noncanonical residue Leu60 in the EF‐hand‐II of TnC1. We therefore propose that, in addition to Ca2+, other regulatory mechanism(s) is required for the full activation of locust flight muscle.

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Section: Introductionmentioning

confidence: 99%

Locusta migratoria flight muscle troponin partially activates thin filament in a calcium‐dependent manner

Liang

2022

Insect Molecular Biology

View full text Add to dashboard Cite

show abstract

Calcium desensitization in cardiac troponin C: a novel role in mouse skeletal muscle

Cited by 1 publication

References 5 publications

Locusta migratoria flight muscle troponin partially activates thin filament in a calcium‐dependent manner

Locusta migratoria flight muscle troponin partially activates thin filament in a calcium‐dependent manner

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