Related Experiment Video
Updated: Sep 20, 2025

Author Spotlight: Isolation of Long Muscle Fibers from Mouse Hindlimb Muscles for Studying Excitation-Contraction Coupling Across Fiber Types
Published on: December 1, 2023
Reprint of: The Content of Troponin, Tropomyosin, Actin, and Myosin in Rabbit Skeletal Muscle Myofibrils
1Department of Muscle Research, Boston Biomedical Research Institute, Boston, Massachusetts, 02114.
Abstract:
A stacking sodium dodecyl sulfate polyacrylamide gel electrophoresis system has been used to resolve and quantify all the major myofibrillar protein components (actin, myosin, tropomyosin, and troponin C, T, and I). Quantification was achieved by densitometry of the fast green-stained gels calibrated with the use of purified proteins. The approximate molar ratios of these proteins in rabbit muscle are: actin : myosin: tropomyosin: troponin T: troponin I: troponin C = 7:1:1:1:1:1. On the basis of these results and available structural information one obtains an estimate of 254 myosin molecules per thick filament.
Related Concept Videos
The Sarcomere
Each...
Actin and Myosin in Muscle Contraction
Overview of Skeletal Muscle
Introduction to Actin
Overview of Myosin Structure and Function
Microscopic Anatomy of Skeletal Muscles
The muscle sarcolemma is a plasma membrane enclosing each muscle cell that conducts electrical signals called action potentials. The sarcolemma extends into the cell to form T-tubules, ensuring the neural impulses are uniformly distributed across the entire muscle...

