Microtubules II (Lecture 21)

Question 1

What are the 2 microtubule based motor proteins.

Answer 1

Kinesins and dyneins

Question 2

True or False: Kinesins and dyneins move along microtubules using ATP hydrolysis as the power source

Answer 2

True

Question 3

True or False: Organelles move along microtubules in any direction.

Answer 3

True

Question 4

Most kinesins power transport toward the + end of the microtubule other then _______.

Answer 4

Kinesin 14

Question 5

True or False: Kinesin-1 always transports vesicles from the (−) end to the (+) end of a stationary microtubule.

Answer 5

True

Question 6

What kinesin is not a motor?

Answer 6

Kinesin 13

Question 7

What kinesin acts to slide?

Answer 7

Kinesin 5

Question 8

In kinesin 1, the head take ______ steps form - to +

Answer 8

16 nm

Question 9

What are the 4 steps to the kinesin cycle?

Answer 9

—  Start: Leading head with no nucleotide bound is tightly associated with the microtubule. Trailing head with ADP bound is weakly associated with the microtubule. — 

Step 1: Original leading head binds ATP. — 

Step 2: Yellow linker region swings forward and docks onto the surface of its associated head domain, thrusting the trailing head forward. — 

Step 3: The new leading head binds weakly to a site 16 nm toward the microtubule (+) end. — 

Step 4: New leading head releases ADP and binds tightly to the microtubule. New trailing head hydrolyzes ATP to ADP and Pi. Pi is released and converts trailing head into a weak-MT binding state.

Question 10

What is the inhibited form of kinesin 1

Answer 10

Head tail interaction

Question 11

What are the 3 steps to Kinesin 1-regulation.

Answer 11

—Step 1: Motor binding to vesicle receptor unfolds kinesin, activating ATPase activity — 

Step 2: Transports cargo toward the (+) end of a microtubule — 

Cargo release: Not yet clear how the motor dissociates from the cargo and folds back into the inhibited state

Question 12

Cytoplasmic ______ transports organelles retrograde, toward the (-) end of microtubules

Answer 12

dynein

Question 13

True or False: Dynein is ATP-dependent, a very large protein and not very diverse compared to myosin and kinesins.

Answer 13

True

Question 14

Cytoplasmic dynein has ______ AAA ATPase in head.

Answer 14

6

Question 15

The ______ is the ATP-dependent change in the position of the linker causes movement of the microtubule-binding stalk.

Answer 15

Force-generation mechanism

Question 16

Since dynein cant bind to cargo on its own, _____ complex links dynein to cargo and regulates activity.

Answer 16

Dynactin

Question 17

Dynactin complex contains what 2 features?

Answer 17

One actin subunit — 

CapZ at (+) end

Question 18

Retrograde transport of late endosome by ______.

Answer 18

Dynein

Question 19

Anterograde transport of secretory vesicle by ______.

Answer 19

Kinesin

Question 20

True or False: Tubulin post-translational modifications stabilize microtubules and regulate ability to interact with motors

Answer 20

True