Calcium is required by two proteins, troponin and tropomyosin, that regulate muscle contraction by blocking the binding of myosin to filamentous actin. In a resting sarcomere, tropomyosin blocks ...

Numerous motor and structural proteins compose a highly ordered structure known as the sarcomere, the basic unit of muscle contraction in heart and skeletal muscles. Sarcomeric myosin heavy chain ...

(A) The basic organization of a sarcomere subregion, showing the centralized location of myosin (A band). Actin and the z discs are shown in red. (B) A conceptual diagram representing the ...