Calcium channels

Question 1

What are a lot of the enzymes in neurons dependent on?

Answer 1

Ca2+

Question 2

What is one of the first points of calcium sensitivity?

Answer 2

Recruitment of vesicles away from the reserve pool

Question 3

What is the trigger for full vesicular fusion?

Answer 3

Ca2+ influx through the channel

Question 4

Extracellular Ca2+ conc?

Answer 4

1.1mM (milimilar)

Question 5

Intracellular resting ca2+ conc?

Answer 5

100nm (nanomolar)

Question 6

What maintains the lower resting intracellular conc of Ca2+ compared to extracellular conc?

Answer 6

Calcium pumps

Question 7

Which calcium pumps maintain its low intracellular resting conc?

Answer 7

Sodium calcium exchanger, calcium channels (VG calcium channels)

Question 8

How do calmodulin and calbindin maintain calcium levels?

Answer 8

Physically–> bind to Ca2+

Question 9

How is it known that calmodulin and calbindin are v important in neuronal functions?

Answer 9

Neurons have a lot more of them than other cell types

Question 10

Which organelle is a Ca2+ store in many cells?

Answer 10

ER

Question 11

Where is the intracellular Ca2+ released from as a result of IP3 signalling?

Answer 11

ER

Question 12

Which organelle is v important for calcium buffering in neurons?

Answer 12

Mitochondria

Question 13

Mitochondrial Ca2+ buffering?

Answer 13

Lot of mitochondrial trafficking into the synapse in response to calcium signalling, and once there they can buffer the Ca2+

Question 14

How does calcium imaging technology work?

Answer 14

Can use Ca2+ chelators which fluoresce when exposed to UV depending on whether they are bound to Ca2+ or not

Question 15

What is Ratiometric imaging?

Answer 15

preload cells w/ Ca2+ indicators
excite at 340nm and 380nm, ratio of emission correlates with calcium level

Question 16

What is Fura-2 (AM)?

Answer 16

calcium chelator, fluoresce when exposed to UV light. (dependent on whether it is bound to calcium or not)

Question 17

Example of a genetically encoded calcium indicator?

Answer 17

Camelelons

Question 18

Use of genetically encoded calcium indicators?

Answer 18

In vivo–> mouse model etc

Question 19

How can the actual Ca2+ conc from the fluorescence imaging?

Answer 19

With two equations

Question 20

Role of calcium microdomain?

Answer 20

Increases fidelity of neuronal calcium exocytosis coupling to the localised calcium entry

Question 21

How can sensing machinery be changed w/o having to change themselves?

Answer 21

Can be closer/further away to the calcium channels

Question 22

Difference in how affected calcium sensing machinery are by buffering?

Answer 22

Further away from Ca2+ channel = more sensitive to buddering

Question 23

What does the channel and SNARE complex being physically associated together ensure?

Answer 23

V tight coupling between VG channel opening and vesicular transmitter release

Question 24

Calcium sensing machinery for small molecule transmitter release?

Answer 24

V tightly coupled

Question 25

Why is the timescale between the Ca2+ entering and the NT being released short?

Answer 25

maintains temporal relationship between AP and signal sent

Question 26

Homosynaptic plasticity?

Answer 26

Plasticity within a single synapse--> molecular changes within a synapse

Question 27

Heterosynaptic plasticity?

Answer 27

Input from other synapses can influence NT release

Question 28

What is facilitation of signalling driven by?

Answer 28

Progressive increase in release due to residual calcium at release site during a train of action potentials (short lasting)

Question 29

Potentiation of signalling?

Answer 29

Building up of Ca2+ locally, within intracellular stores-> can provide Ca2+ to facilitate transmission

Question 30

Depression of signalling?

Answer 30

Progressive decrease in release during a train of action potentials due to decline in readily releasable vesicle pool