[A quantitative approach to understand the ultramicro-structure responsible for input mechanism in excitation-contraction (E-C) coupling, on the basis of physio-morphological observations].
Our morphophysiological studies using concanavalin A-ferritin (Con A-F) have indicated that: (1) an out- and up-ward movement of a movable structure at the luminal surface-portion of the T-tubular membrane opposite the feet initiates contraction; (2) the grade of the movement depends on that of depolarization; (3) the movable structure is essentially a 'moving arm', which is fixed in wall of T-tubules at its fixed end and is able to be bound to the Con A-moiety of Con A-F particle about at its free end. Calculation based on molecular morphology and behaviour of Con A-F particle revealed following points: If (a) the origin of coordinate be the intersection of longitudinal center line of foot and the surface of T-tubular membrane in the transverse section of the tubules, (b) the fixed point of the arm is exactly on the surface of T-tubular membrane, and (c) the movement takes place in the transverse direction to the longitudinal axis of T-tubules, (1) the location of the center point of the movement of the moving arm is at 5.4 nm in the outside direction from the origin, (2) the arm is about 4 nm in length and moves by about 2.4 nm up- and out-ward at its free end upon about complete depolarization.
Arima
T
T
1st Department of Physiology, National Defense Medical College, Saitama, Japan.
Fujino
M
M
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D003208:Concanavalin A / Q000378:metabolism; D005293:Ferritins / Q000378:metabolism; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000502:physiology*; D009124:Muscle Proteins / Q000502:physiology*; D009132:Muscles / Q000648:ultrastructure; D010658:Phenylglyoxal / Q000378:metabolism; D011485:Protein Binding; D011898:Ranidae
D009124:Muscle Proteins; D003208:Concanavalin A; D005293:Ferritins; D010658:Phenylglyoxal