Rho GTPases are the “master builders” of the cell because they can activate an array of kinases and cytoskeletal binding proteins that remodel cytoskeletal elements to alter cell shape and movement

TLS Online TPP Program

#Id: 8412

#XL - Q Biochemistry

Binding of Ca2+ ions to TN-C

triggers movement of TM to a new position on the filament, thereby exposing the myosin-binding sites on actin.

TLS Online TPP Program

#Id: 8411

#XL - Q Biochemistry

In the absence of Ca2+, muscle is relaxed

TM blocks myosin’s interaction with F-actin

TLS Online TPP Program

#Id: 8410

#XL - Q Biochemistry

TN-C is the calcium-binding subunit, controls the

position of TM on the surface of an actin filament through the TN-I and TN-T subunits

TLS Online TPP Program

#Id: 8409

#XL - Q Biochemistry

Troponin, a complex of three polypeptides, 

TN-T (tropomyosin-binding)

TN-I  (inhibitory)

TN-C (Ca2+-binding)

TLS Online TPP Program

#Id: 8408

#XL - Q Biochemistry

Tropomyosin (TM) is a ropelike molecule, about 40 nm in length, binds to 7 actin subunits in an actin filament.

TLS Online TPP Program

#Id: 8406

#XL - Q Biochemistry

Vertebrate skeletal muscle contraction, also depends on set of specialized accessory proteins that are closely associated with the actin thin filaments:

a) Tropomyosin

b) Troponin