Cell Biology: Cytoskeletal Motors Vocabulary

Flashcards on Cell Biology: Cytoskeletal Motors

Myosin

Actin motor protein that uses ATP hydrolysis to move along actin filaments.

Mechanochemical enzymes

Enzymes that convert chemical energy into mechanical energy; also known as motor proteins.

Myosin Structure

Composed of one or two heavy chains and several light chains, organized into head, neck, and tail regions.

Myosin Head

Contains an actin binding region and a nucleotide binding site for ATP; responsible for force generation.

Myosin Neck

α-helical region that associates with light chains, regulating the activity of the head domain.

Myosin Tail

Contains binding sites that determine the specificity of the myosin.

Rigor mortis

Muscle stiffness in death due to myosin heads firmly attached to actin filaments in the absence of ATP.

Power stroke

Release of Pi and elastic energy by the myosin head, moving the actin filament.

Sarcomere

Contractile unit in skeletal muscle fibers, consisting of Z disk, I bands, and A band.

Z disk

The end of a sarcomere, shared with adjacent sarcomeres.

I bands

Region of actin thin filaments anchored to the Z disk.

A band

Myosin thick filaments interdigitated with thin filaments.

Tropomyosin (TM)

Coiled-coil dimer that lies along the muscle thin filament, blocking or allowing myosin head cross-bridge cycle.

Troponin

A three-peptide protein complex bound to tropomyosin (TM); controls the TM position via TN-C, TN-I, and TN-T.

Kinesin

Microtubule motor protein that uses ATP to move processively towards the +ve end of microtubules.

Dynein

Minus end directed microtubule motor protein involved in organelle movement, positioning centrosome and nucleus, and construction of microtubular spindle.

Dynactin complex

A large multi-subunit complex required by cytoplasmic dynein to move cargo.