Intracellular Microtubule Based Movement: Kinesin and Dynen

Question 1

what do microtubules (MTs) provide?

• traffic towards the minus end?
• traffic towards the plus end?

Answer 1

provide a rigid set of tracks for transport of a variety of membrane-enclosed organelles and vesicles

• towards the minus end of the MT is considered “in bound”
• towards the plus end is considered “out bound” (directed toward the periphery of the cell)

Question 2

Microtubule associated motor proteins:

-attach to… and then…

Answer 2

-attach to vesicles or organelles and then “walk” along the MT, using ATP to provide the needed energy

Question 3

proteins or neurotransmitters synthesized in the cell body of the neuron must be…? by a process called?

Answer 3

transported to the nerve ending –> process called fast axonal transport, which involves the movement of vesicles and other organelles along MTs

Question 4

two proteins responsible for fast axonal transport are…what are they involved in?

Answer 4

1. kniesin 1 is involved in ATP dependent transport toward the plus end ( away from centrisome) –> anterograde axonal transport
2. cytoplasmic dyenin moves particles (cargo) in the oppostire direction ( retrograde axonal transport)

Question 5

Dyenins can be grouped into two major classes..

Answer 5

1. axonemal dyenin

2. cytoplasmic dyenin

Question 6

Cytoplasmic dyenin..?

• moves toward..?
• associated with?

Answer 6

• moves towards the minus end of the MTs (in contrast to kinesins)
• associated with the protein complex called dynactin, which helps link it to cargo

Question 7

Axonemal dyenin: includes at least how many types?

Answer 7

4

Question 8

How do motor proteins move along MTs?

Answer 8

by hydrolyzing ATP

Question 9

Kinesins consist of three parts:

Answer 9

1. globular head region that attaches to MTs
2. coiled helical region
3. light chain region involved in attaching the kinesis to other proteins or organelles

Question 10

Kinesins move along MTs in 8nm steps, the movement is coupled to..?

Answer 10

coupled to ATP hydrolysis

Question 11

what does the walking of kinesins look like?

Answer 11

movement looks like “walking” with the 2 globular head domains taking turns as the front foot

Question 12

kinesins walking involves..

Answer 12

releasing bound ATP, acquiring new ATP, cycle repeats!

this is how they can move long distances before detaching from it