Lecture 6.1

Question 1

Where does NGF bind and where does it act?

Answer 1

It binds at the synapse and acts on the nucleus with retrograde signalling

Question 2

What are the components of the axonal skeleton?

Answer 2

Microfilaments within the terminals, intermediate filaments and microtubules

Question 3

What is spectrin?

Answer 3

Support for the cell membrane of the axonal skeleton

Question 4

What are the 3 functions of Microtubules?

Answer 4

Axonal transport
Contribute to cell shape
Shuttle organelles inside the cell body

Question 5

How many filaments make up a microtubule?

Answer 5

13

Question 6

Where do microtubules originate in the cell?

Answer 6

At the centriole at the negative end

Question 7

Describe the beta end of a microtubule

Answer 7

+ end, undergoes extension and shortening

Question 8

Describe the alpha end of a microtubule

Answer 8

• end and is the site of anchoring

Question 9

Can you have bi directional transport on a microtubule?

Answer 9

yes

Question 10

To what types of cargo can fast transportation occur?

Answer 10

Only membrane bound cargo ex/ Vesicles or organelles

Question 11

What 2 proteins carry vesicles along the outside of microtubules and what do they need to function?

Answer 11

Kinesins and Dyneins

ATP

Question 12

Transport occurs in ….nm hops

Answer 12

5nm (between Dyneins)

Question 13

Describe the characteristics of Kinesins

Answer 13

They are used in forward movement, need ATP to function, move along a single protofilament of the micrtotubule

Question 14

Describe the characteristics of Dyneins

Answer 14

For retrograde movement, need ATP

Question 15

What is the role of the head part of a Kinesin?

Answer 15

To act as the motor by hydrolyzing ATP

Question 16

Can forward and backward transport occur on one microtubule?

Answer 16

Yes, vesicle do cross without collision

Question 17

What happens in retrograde transport and give an example of this?

Answer 17

Membrane bound vesicles are returned to the cell body from the distal axon
Retrieval of synaptic vesicle membranes of peptide neurotransmitters

Question 18

In what direction is slow axonal transport?

Answer 18

Only in forward transport

Question 19

What proteins use slow axonal transport?

Answer 19

Structural proteins ex/ Neurofilament

Question 20

Is slow axonal transport efficient?

Answer 20

Nope

Question 21

Neural circuits are dependent on ……..

Answer 21

Neurotrophin and activity

Question 22

What is an example of a neurotrophin and what is its receptor?

Answer 22

Nerve growth factor and TrkA

Question 23

Describe the retrograde signalling of NGF and TrkA

Answer 23

NGF comes into the distal axon by binding to TrkA. NGF forms in the center of a vesicle that is surrounded by TrkA receptors. As the vesicle moves back up the axon i na retrograde fashion, the vesicle is continuously signalling due to active TrkA. The vesicle reaches the nucleus in the cell body and enters the gene expression cycle leading to an increase in signalling for an increase in neurotransmitter production

Question 24

Describe the 4 Neurotrophin examples and their receptors

Answer 24

NGF-Trk A
BDNF- TrK B
NT3- TrK C
NT4- TrK B

Question 25

Is TrKA the only receptor when acting with neurotrophins

Answer 25

No, co-receptor is p75, this increases sensitivity

Question 26

What occurs in the absence of TrK receptors?

Answer 26

Cell death

Question 27

What are the actions of Neurotrophins in the developing nervous system?

Answer 27

Neuronal differentiation, neuronal survival, neuronal guidance, axonal growth

Question 28

What are the actions of Neurotrophins in the mature nervous system?

Answer 28

Axonal growth and maintaining normal neuronal function

Question 29

What occurs with withdrawal of Neurotrophin in mature neurons?

Answer 29

Decreased transmitter production/transmitter release
Retraction of axonal branches
Reduction in cell body size

Question 30

What are NGF targets?

Answer 30

Nociceptive sensory neurons
Sympathetic ganglia
Cholinergic neurons in basal forebrain

Question 31

Describe the anatomy of NGF

Answer 31

Two identical 118 amino acid monomers that are back to back
They are bound due to when they come together, each monomer has a TrkA receptor binding site in which the two sites come together