Question

Note on structure of contractile protein

Answer 1

Three types of proteins form myofibrils: contractile, regulatory, and structural.Contractile proteins generate force for muscle contraction. The two contractile proteins in myofibrils are actin (part of the thin filament) and myosin (part of the thick filament).

Answer 2

$\large{\underline{\rm{\pink{Structure\;of\:contractile\:proteins:-}}}}$

● An actin filament is made of 2 filamentous actins which form double helix.

● F-actin is a polymer of monomeric Globular actins.

● Actin contains 2 other proteins. Two filaments of tropomyosin run along the grooves of the F-actin double helix.

● Troponin are having 3 subunits which is seen at regular intervals on tropomyosin. In the resting state a subunit of troponin masks the binding sites for myosin on the actin filaments.

● Each myosin filament is a polymer of many monomeric proteins called Meromyosins.

● A meromyosin has 2 parts:-

→ Heavy meromyosin or HMM or cross arm.

→ The globular head is an active ATPase enzyme and has binding sites for ATP and active sites for actin.