MUSCLE PHYSIOLOGY

Detailed explanation-1: -Tropomyosin blocks myosin binding sites on actin molecules, preventing cross-bridge formation and preventing contraction in a muscle without nervous input. Troponin binds to tropomyosin and helps to position it on the actin molecule; it also binds calcium ions.

Detailed explanation-2: -1 Tropomyosin. TM regulates smooth muscle contraction by blocking the myosin binding sites on actin, preventing actin–myosin interaction.

Detailed explanation-3: -The tropomyosin coiled coil binds end-to-end to form continuous strands along both sides of the actin filament, such that one molecule spans the length of seven actin monomers.

Detailed explanation-4: -Tropomodulin: a cytoskeletal protein that binds to the end of erythrocyte tropomyosin and inhibits tropomyosin binding to actin.

Detailed explanation-5: -In skeletal and cardiac muscle, calcium binding to troponin causes a shift in tropomyosin’s position along actin, exposing myosin binding sites and thereby facilitating muscle contraction (Lehman, Craig et al.