6 - Overview of the signalling pathways in the CNS

Question 1

What is the difference between inter and intra-cellular signalling?

Answer 1

inter-cellular = "between cell"
intra-cellular = "inside cell"

Question 2

What are the most abundant excitatory and inhibitory neurotransmitters in the hypothalamus?
And what type of neurones are they transmitted by?

Answer 2

Excitatory = Glutamate - Spiny neurones
Inhibitory = GABA - Non-spiny neurones

Question 3

Forms of inter-cellular signalling: Give 1 example of:
Direct cell to cell contact
Secreted ligands
Synaptic transmission

Answer 3

Direct - Adhesion molecules, electric fields
Secreted - Neurotransmitters, netrins, trophic factor
Synaptic - Neurotransmitters

Question 4

What are the 2 major classes of synapses?

Answer 4

Electrical synapses

Chemical synapses

Question 5

What are the most common

a) Excitatory synapses
b) Inhibitory synapses

Answer 5

Glutamatergic

GABAergic

Question 6

What is the structural difference between Glutamate and GABA

Answer 6

They both have a 3 carbon chain with COOH and NH2 terminals, but
Glutamate has an extra COOH because it’s an amino acid.

Question 7

Which types of receptors regulate ion channels?

Give some examples.

Answer 7

Ionotripic

GluR, GABAR, ATPR

Question 8

Which types of receptors regulate the metabolism?
Give an example
a) in the membrane
b) inside the cell

Answer 8

Metabotropic
Membrane = G protein linked, enzyme linked
Cell = guanylyl cyclase, hormone receptors

Question 9

Draw the allosteric NMDA receptor

include antagonists, modulatory cites, receptor site and any other features

Answer 9

Lecture slide

Includes, Glutamate +, MG2+ -, Channel blocking drugs, Na+, Ca2+, Glycine, Polyamines

Question 10

Draw the allosteric GABAa receptor

include antagonists, modulatory cite, receptor site and any other features

Answer 10

Lecture slide
Includes: GABA +, Cl-, Channel blocking drugs, Benzodiazepine agonists, antagonists, benzodiazepine inverse agonists, channel modulators.

Question 11

Give some an example of a

a) Voltage gated ion channel
b) Transmitter-gated ion channel
c) Transmitter+voltage gated ion channel

Answer 11

a) Calcium/sodium/potassium channels
b) AMPAR/ cholinergic nicotinic etc.
c) NMDAR

Question 12

Give some a) extracellular b) intracellular sources of calcium

Answer 12

Extracellular = NMDAR and vdCC
Intracellular = RyR, IP3R

Question 13

What are some functions mediated by G-protein linked receptors at the intra and extracellular level? (5)

Answer 13

Neurotransmission
Cell growth and differentiation
Reorganisation of cytoskeleton
Intracellular transport
exo and endocytosis

Question 14

What are the two kinds of G-proteins?

Answer 14

1) Hetero G-proteins

2) Small G-proteins

Question 15

Small G proteins are a superfamily of ____ proteins.

They are regulators of _____ transduction, leading to organisation of ______ and _______.

Answer 15

Small G proteins are a superfamily of switchproteins.

They are regulators of signal transduction, leading to organisation of the cytoskeleton and cellular traffic.

Question 16

What are some of the members (and their functions) of the small G protein family? (5)

Answer 16

Ras - cell proliferation and differentiation
Rabs - directionality of transport
Arfs - vesicular trafficing, activation of phospholipase B
Rhos/Racs - regulation of cytoskeleton
Rans - regulation of nucleocytoplasmic transport of RNA and proteins during the G1, S, and G2 phases of the cell cycle and microtubule organization during the M phase.

Question 17

What is the function of the Rans G protein?

Answer 17

Regulation of nucleocytoplasmic transport of RNA and proteins during the G1, S, and G2 phases of the cell cycle and microtubule organization during the M phase.

Question 18

What are some benefits, and 1 drawback of the G-protein system?

Answer 18

Benefits:
Amplification of signal, great environment for regulation, long lasting, highly conserved.
Drawback: Slower than other signalling systems

Question 19

Draw the EGF transduction pathway (example of metabotropic action with use of small G-protein)

Answer 19

lecture slide
EGF receptor, tyrosine kinase domain, Grb-2 adapter protein, SoS (guanine nucleotide exchange factor), GDP-GTP(ras->activated Ras)