Tilting of the light-chain region of myosin during step length changes and active force generation in skeletal muscle

• Published in: Nature (London) 1995-06, Vol.375 (6533), p.688-691
• Main Authors: Irving, Malcolm, St Claire Alien, Taylor, Sabido-David, Cibele, Craik, James S, Brandmeier, Birgit, Kendrick-Jones, John, Corrie, John E. T, Trentham, David R, Goldman, Yale E
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biomechanical Phenomena; Cellular biology; Chickens; Escherichia coli; Fluorescence; Fluorescence Polarization; Fundamental and applied biological sciences. Psychology; Humanities and Social Sciences; In Vitro Techniques; letter; multidisciplinary; Muscle Contraction - physiology; Muscle, Skeletal - physiology; Muscular system; Myosins - physiology; Rabbits; Recombinant Proteins; Rhodamines; Sarcomeres - physiology; Science; Science (multidisciplinary); Skeletal system; Space life sciences; Striated muscle. Tendons; Vertebrates: osteoarticular system, musculoskeletal system
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/375688a0

FORCE generation and relative sliding between the myosin and actin filaments in muscle are thought to be caused by tilting of the head region of the myosin crossbridges between the filaments 1–3 . Structural and spectroscopic experiments have demonstrated segmental flexibility of myosin in muscle 4–6 , but have not shown a direct linkage between tilting of the myosin heads and either force generation or filament sliding. Here we use fluorescence polarization to detect changes in the orientation of the light-chain region of the head, the part most likely to tilt 5,7,8 , and synchronized head movements by imposing rapid length steps 9–11 . We found that the light-chain region of the myosin head tilts both during the imposed filament sliding and during the subsequent quick force recovery that is thought to signal the elementary force-generating event.