title: 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).
mesh_terms: D000818:Animals; D002645:Chickens; D008854:Microscopy, Electron / Q000379:methods; D008855:Microscopy, Electron, Scanning / Q000379:methods; D009132:Muscles; D009218:Myosins / Q000302:isolation & purification; D011487:Protein Conformation
chemical_list: D009218:Myosins