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NSCI200: Neuroscience I > Secondary Messengers > Flashcards

Secondary Messengers Flashcards

1
Q

Secondary messengers mediate ___ signalling

A

intracellular

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2
Q

List 3 types of indirect transmission of signals

A

1) endocrine signalling
2) paracrine signalling
3) synaptic signalling

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3
Q

List 3 types of signalling molecules

A

1) cell impermeant molecules - require a receptor
2) cell permeant molecules - molecule diffuses right across membrane
3) cell surface signalling molecules - signaling occurs through direct binding of 2 cells close together

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4
Q

Is GPCR signalling slow or fast? Why?

A

Slow due to the time it takes to generate a signal cascade

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5
Q

Is ionotropic signalling considered fast or slow? Why?

A

Fast bc the ion channel opens, immediately allowing ions to flow through which allows the cell to quickly summate it and turn the signal into “make AP” or “don;t make AP”

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6
Q

Where in the synapse are metabotropic receptors located?

A

perisynaptic/peripheral area

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7
Q

T or F: activating only a few metabotropic receptors will yield a large effect

A

T

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8
Q

T or F: activating only a few ionotropic receptors will yield a small effect

A

T

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9
Q

Where is the NT binding site located on metabotropic receptors?

A

Middle of the channel

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10
Q

Do metabotropic receptors have large extracellular domains?

A

No

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11
Q

What do GAP proteins do?

A

Controls speed of GTP hydrolysis (GTP is bound to monomeric G protein)

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12
Q

Which enzyme is responsible for replacing GDP on monomeric G protein with GTP?

A

GEF

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13
Q

Name a common monomeric G protein

A

Ras

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14
Q

In a heterotrimeric G protein, which subunit acts as the GTPase?

A

alpha

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15
Q

Which subunit in a heterotrimeric G protein binds GTP?

A

alpha

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16
Q

What acts the GEF in a heterotrimeric G protein?

A

GPCR - activated GPCR allows alpha-GDP to be replaced with GTP

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17
Q

T or F: Only the alpha subunit of a G protein can activate downstream effectors

A

F - the beta/gamma subunit can as well

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18
Q

Which subunit of a heterotrimeric G protein is membrane bound?

A

Gamma

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19
Q

In basal state (ie not bound to a NT), is the GPCR associated with a G protein?

A

No

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20
Q

What does the Gi subunit do?

A

Inactivates adenylyl cyclase, leading to decreased cAMP production

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21
Q

What does Gq do?

A

Activates PLC, which generates IP3 + DAG

22
Q

What kind of enzymes cleave IP3 to stop it from signalling? What is it cleaved into?

A

Phosphatases; inositol

23
Q

Which molecule is DAG and IP3 generated from?

A

PIP2

24
Q

Is DAG transmembrane or soluble?

A

transmembrane

25
Q

What does DAG activate?

A

PKC

26
Q

Which cycle do IP3 and DAG undergo to regenerate PIP2?

A

Phosphoinositol cycle

27
Q

Which ion can be used to block the phosphoinositol cycle?

A

lithium

28
Q

Which alpha subunit can be used to turn on ECB production?

A

Gq

29
Q

In PKA, what does the regulatory domain act as?

A

pseudosubtrate to prevent catalytic kinase domain from being active all the time

30
Q

Describe how GPCR signalling affects PKA activity

A
  1. alpha subunit (Gs) activates AC
  2. AC generates more cAMP
  3. cAMP binds to regulatory domain on PKA, causing conformational change that releases the catalytic domain
31
Q

Which calcium binding protein activates CaMKII?

A

calmodulin

32
Q

PKC is activated by ___ and coactivated by ___

A

DAG, Calcium

33
Q

Name 4 categories of cellular receptors

A
  1. channel linked receptors/ionotropic
  2. enzyme linked receptors (ex. RTKs)
  3. intracellular receptors
  4. GPCRs/metabotropic
34
Q

T or F: Ca is an intracellular secondary messenger

A

T

35
Q

Name 2 sources of Ca:

A
  1. extracellular space

2. ER

36
Q

T or F: Normally, intracellular concentrations of Ca are quite how

A

F - they are normally LOW

37
Q

List 5 intracellular targets of Ca

A 
Synaptotagmin
kinases
phosphatases
calmodulin 
ion channels
38
Q

List 3 Ca removal mechanisms

A

1) Ca exchangers and Ca pumps on plasma membrane
2) Ca pumps on ER membrane
3) mitochondria acts as a temporary Ca sink

39
Q

List a ligand-gated channel that will allow Ca to enter the cell

A

NMDA, an ionotropic glutamate receptor

40
Q

What activates the ryanodine channel on ER?

A

Calcium - generates a positive feedback loop for Ca release

41
Q

How will an axon terminal with many mitochondria affect the length of time that the NT signals for?

A

The mt will sequester the Ca which is needed for NT release, therefore the synapse will not be able to signal for very long

42
Q

How will an axon terminal with few mt affect signalling?

A

Ca will rise quickly because there are less mt to sequester it, therefore more signalling will occur since more vesicle fusion will occur

43
Q

If you want more release of dense core vesicles, would your axon terminal require more or less mitcohondria?

A

Less - allows Ca levels to rise more quickly

44
Q

What is the main purpose of CaMKII autophosphorylation?

A

Maintenance of Ca signal even after Ca is gone

45
Q

T or F: many interneurons contain buffering CBP

A

T

46
Q

Do buffering CBP cause downstream signalling?

A

No

47
Q

Which proteins may be used to label interneurons?

A

Buffering CBP

48
Q

How to Ca-binding dyes work?

A

They change their fluorescence when they bind to Ca

49
Q

High Ca levels will result in increased phosphorylation or dephosphorylation?

A

High Ca –> activate kinases –> high phosphorylation

50
Q

Low Ca levels will result in increased phosphorylation or dephosphorylation?

A

Low Ca –> activate phosphatases –> high dephosphorylation

NSCI200: Neuroscience I (5 decks)

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