Actin Myosin Crossbridge 3D Animation

The Animation

Legend

See an Explanatory Image Sequence Below | View a QuickTime Animation instead

Explanatory Image Sequence
(based in part on
Color Atlas of Physiology, Agamemnon Despopoulos, Stefan Silbernagl
Thieme Medical Publishers, Inc. , 1991, New York)

Calcium ion approaches Troponin.
Calcium ion activates Troponin to expose binding site for Myosin head.
Troponin activation by calcium exposes binding site for Myosin head. Magnesium ion approaches Myosin head.
Myosin head binds with Actin filament. Magnesium ion activates Myosin head causing release of Phosphorus ion from ATP leaving ADP and causing the Myosin head to contract.
Magnesium ion and ADP released from Myosin head, ending its contraction.
Myosin head releases from Actin filament. Calcium ion released from Troponin, allowing it to cover binding site. New calcium ion approaches next Troponin molecule. New ATP molecule approaches Myosin head, beginning the process over again.