Question

Label the correct parts of the Myosin monomer :

• A. A. Cross arm
  B. Actin binding site
  C. Head
  D. ATP binding site
• B. A. Head
  B. Cross arm
  C. Actin binding site
  D. ATP binding site
• C. A. Actin binding site
  B. Head
  C. ATP binding site
  D. Cross arm
• D. A. ATP binding site
  B. Actin binding site
  C. Head
  D. Cross arm

Answer 1

The correct option is B A. Head

B. Cross arm
C. Actin binding site
D. ATP binding site

• Each actin (thin) filament is made of two filamentous actins helically wound to each other. Each ‘F’ actin is a polymer of monomeric ‘G’ (Globular) actins.
• There are two important parts, a globular head (here, labelled as A) with a short arm and a tail, the former being called the heavy meromyosin (HMM) and the latter, the light meromyosin (LMM).
• The HMM component, i.e., the head and short arm projects outwards at a regular distance and angle from each other from the surface of a polymerised myosin filament and are known as the cross arm (here, labelled as B).
• The globular head is an active ATPase enzyme and has binding sites for ATP (here, labelled as D) and active sites for actin(here, labelled as C).

Thus, the correct answer is option B.