Question

This noncontractile protein stabilizes actin and extends from the Z line but not to the M line.

	a.	Connectin
	b.	Nebulin
	c.	Myosin
	d.	Light chain

Answer 1

Option b-Nebulin

Nebulin is an actin-binding protein which is localized to the thin filament of the sarcomeres in skeletal muscle. Because its length is proportional to thin filament length,nebulin acts as a thin filament ruler and regulates thin filament length during sarcomere assembly and acts as the coats the actin filament.Nebulin is a giant filamentous protein found in skeletal muscle where it spans from the sarcomere's Z-disk to near the tip of the thin filament,not extend upto M line.

Titin known as connectin, is a  giant protein, greater than 1 µm in length, that functions as a molecular spring which is responsible for the passive elasticity of muscle in addition to keeping myosin molecules in place.

Myosins  are a superfamily of motor proteins best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes.