Distribution of myosin heads on the surface of vertebrate skeletal muscle thick filaments
Skubishak, L.
Biofizika 41(3): 695-703
1996
ISSN/ISBN: 0006-3029 PMID: 8924471 Document Number: 466653
Different mutual displacements (configurations) between three myosin crossbridges belonging to the same crown and the angles of rotation between succeeding crowns in relaxed vertebrate skeletal thick filament have been analysed by computer simulation. Model corresponding to configuration 0 degrees/120 degrees/180 degrees and the angle of -120 degrees reveals the best consistency with experimental data in comparison with the model corresponding to previously proposed configuration and angle, i.e. 0 degrees/120 degrees/240 degrees and 40 degrees, correspondingly. According to the new scheme of the myosin molecule packing into thick filament, all myosin heads are arranged along the wide helical tracks with an axial repeat of 43 nm and with the slope angle of approximately 68 degrees. Along each helical track there are 5 subunits. In contrary to the widely accepted model where 9 crossbridges with the angular separation of 40 degrees surround each thick filament, there are 6 myosin crossbridges separated by 60 degrees around a thick filament. Therefore, all myosin crossbridges interact with corresponding actin monomers of six surrounding thin filaments during muscle contraction.