ANATOMY

Detailed explanation-1: -The thick filament consists largely of myosin. Six proteins make up myosin: two heavy chains whose tails intertwine to form a supercoil and whose heads contain actin binding sites and a catalytic site for ATP hydrolysis. Two myosin light chains bind to each head region.

Detailed explanation-2: -So, the correct answer is ‘Head of heavy meromyosin’.

Detailed explanation-3: -The I bands contain only thin (actin) filaments, whereas the A bands contain thick (myosin) filaments. The myosin and actin filaments overlap in peripheral regions of the A band, whereas a middle region (called the H zone) contains only myosin.

Detailed explanation-4: -In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles.