Contraction of striated muscle is regulated by a dual mechanism involving both thin, actin-containing filament and thick, myosin-containing filament. Thin filament is activated by Ca2+ binding to troponin, leading to tropomyosin displacement that exposes actin sites for interaction with myosin motors, extending from the neighbouring stress-activated thick filaments. Motor attachment to actin contributes to spreading activation along the thin filament, through a cooperative mechanism, still unclear, that determines the slope of the sigmoidal relation between isometric force and pCa (-log[Ca2+]), estimated by Hill coefficient nH. We use sarcomere-level mechanics in demembranated fibres of rabbit skeletal muscle activated by Ca2+ at different temperatures (12-35 °C) to show that nH depends on the motor force at constant number of attached motors. The definition of the role of motor force provides fundamental constraints for modelling the dynamics of thin filament activation and defining the action of small molecules as possible therapeutic tools.

The force of the myosin motor sets cooperativity in thin filament activation of skeletal muscles / Marco Caremani , Matteo Marcello , Ilaria Morotti , Irene Pertici , Caterina Squarci , Massimo Reconditi , Pasquale Bianco , Gabriella Piazzesi , Vincenzo Lombardi, Marco Linari. - In: COMMUNICATIONS BIOLOGY. - ISSN 2399-3642. - ELETTRONICO. - (2022), pp. 0-0.

The force of the myosin motor sets cooperativity in thin filament activation of skeletal muscles

Marco Caremani;Matteo Marcello;Ilaria Morotti;Irene Pertici;Caterina Squarci;Massimo Reconditi;Pasquale Bianco;Gabriella Piazzesi;Vincenzo Lombardi
;
Marco Linari
2022

Abstract

Contraction of striated muscle is regulated by a dual mechanism involving both thin, actin-containing filament and thick, myosin-containing filament. Thin filament is activated by Ca2+ binding to troponin, leading to tropomyosin displacement that exposes actin sites for interaction with myosin motors, extending from the neighbouring stress-activated thick filaments. Motor attachment to actin contributes to spreading activation along the thin filament, through a cooperative mechanism, still unclear, that determines the slope of the sigmoidal relation between isometric force and pCa (-log[Ca2+]), estimated by Hill coefficient nH. We use sarcomere-level mechanics in demembranated fibres of rabbit skeletal muscle activated by Ca2+ at different temperatures (12-35 °C) to show that nH depends on the motor force at constant number of attached motors. The definition of the role of motor force provides fundamental constraints for modelling the dynamics of thin filament activation and defining the action of small molecules as possible therapeutic tools.
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Marco Caremani , Matteo Marcello , Ilaria Morotti , Irene Pertici , Caterina Squarci , Massimo Reconditi , Pasquale Bianco , Gabriella Piazzesi , Vincenzo Lombardi, Marco Linari
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2158/1286774
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