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Updated: Aug 31, 2026

Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays
Published on: February 4, 2021
Unshadowed myosin molecules: STEM mass-maps of myosin heads
Abstract:
Myosin molecules were directly visualized without heavy metal shadowing by scanning transmission electron microscopy (STEM) under low dose conditions. The general appearance and dimensions of heavy metal-free molecules were similar to those of shadowed myosin, either after freeze-drying without or air-drying with glycerol. Two characteristic configurations of myosin head regions were found, a first type showing two pear-shaped heads with narrow necks and a second type showing two heads connected by an extra mass in the central regulatory domain where the light chains are located. The mass of the latter type (mol. wt. = 265 +/- 39 kd) is in excellent accordance with biochemical data whereas the mass of the first type is somewhat lower (mol. wt. 219 +/- 44 kd).
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