The mechanochemical enzyme that can be found on the surfaces of cellular organelles where it mediates movement toward the plus end of microtubules is which of the following?
1.Myosin (myosin II)
2.Minimmyosin (myosin I)
3.Dynein
4.Kinesin
5.Filamin
Kinesin moves vesicles unidirectionally from the minus end to the plus end of the microtubule—for example, from the cell body to the axon terminus in fast axonal transport. Myosin, minimyosin, dynein, dynamin, and kinesin (answers a, b, c, and e) are all mechanochemical enzymes or molecular “motors” that hydrolyze ATP and undergo conformational changes that are converted into movement. Cytoplasmic dynein is responsible for movement toward the minus end of the microtubules. Remember kinesin kicks out and dynein drags them in (see feedback to question 41). Ciliary and flagellar bending is the classic model for microtubule-based motility. The motor is dynein, which causes the relative sliding between microtubules in the axoneme. Structural constraints within the axoneme as a whole convert sliding into ciliary bending.
Dynamin is another ATPase motor that mediates sliding between adjacent cytoplasmic microtubules. Filamin or other actin cross-linking proteins form a gel network in the cell cortex (the area just beneath the cell membrane). The presence of the actin gel in the cell cortex contributes to the rigidity of the cell and is also involved in changes in cell shape and chromosome movements during mitosis.The sarcomere extends from Z disc (line) to Z disc. The H band is located between the ends of the thin (actin) filaments. The A band is defined by the width of the thick (myosin) filaments. The I bands are not shown completely on the figure because they are found between adjacent A bands.