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Biomed Season Finale > Molecular Pharmacology - Synaptic Receptors > Flashcards

Molecular Pharmacology - Synaptic Receptors Flashcards

1
Q

what are the features of dendrites

A

input - afferent
short and multiple processes
markers - MAP2
postsynaptic spines

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2
Q

what are the features of axons

A

output - efferent
thinner and longer than dendrites
markers - Tau
postsynaptic terminals

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3
Q

function of basket cells

A

they target alpha-1 receptors
regulate the generation of action potentials from pyramidal neurones in layer 5

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4
Q

what is an experimental method to study heterologous receptors using HEK cells

A

transfect the HEK cells with plasmids carrying the sequence of interest and a fluorescent marker (GFP)
wait ~3 days for expression and membrane insertion of protein channels

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5
Q

what is an experimental method used to study heterologous receptors using oocytes

A

microtransplantation:
take human tissue - extract the mRNA of interest
inject said mRNA into xenopus oocyte
wait for expression to study receptor of interest

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6
Q

outline the brain slice technique

A

brain is rapidly extracted and sliced in ice-cold cerebrospinal fluid
slices survive for up to 12 hours

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7
Q

what are the pros of the brain slice technique

A

network connectivity is preserved
anatomically identifiable regions
allows for single cell recording and identification of cells

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8
Q

what glutamate receptors are responsible for fast excitation

A

AMPA
Kainate

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9
Q

what glutamate receptor is responsible for coincidence detection

A

NMDA

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10
Q

what are iGluR

A

selective cationic channels

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11
Q

what is the reversal potential for cationic channels in neurones

A

0mV

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12
Q

what happens when cationic channels in neurones open

A

the cell depolarises - brings the cell closer to threshold
- generates excitatory effect

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13
Q

what is permeability of all ion channels dictated by

A

the ion channel molecule

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14
Q

what is decay time

A

how long does the receptor hold onto the neurotransmitter

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15
Q

what is the decay time for AMPA and NMDA

A

AMPA - 3ms
NMDA - 40-2000ms

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16
Q

where is the C-terminus of GABA receptors located (AMPA/NMDA)

A

located intracellularly
important for scaffolding and function

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17
Q

what is the overall structure of glutamate receptors

A

3 transmembrane domains
1 reentrant loop
intracellular C-terminus
extracellular N-terminus
ligand binding domain is made from N-terminus region S1 and S2

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18
Q

what is required for AMPAR activation

A

binding of one glutamate to subunit to open the AMPA pore
conductance (g=I/V) is agonist dependent

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19
Q

what is required for NMDAR activation

A

2 molecules of glutamate must bind to GluN2 subunits
2 molecules of glycine - co-agonist - must bind to GluN1 subunits, D-serine can also serve this function
conductance of NMDAR is agonist independent

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20
Q

what does conductance mean

A

if something’s conductance is agonist dependent then the amount of agonist influences the degree to which the receptor/pore is activated/opened and vice versa for independent

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21
Q

outline the conductance of AMPA

A

so there are 4 subunits to AMPA, each with a glutamate binding site
if one glutamate is bound then 1 quarter of the pore is open, the more glutamate bound to each unit the more the pore opens

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22
Q

what is the S1 and S2 regions connected by

A

a glycine-threonine linker

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23
Q

why are NMDAR voltage dependent

A

because of Mg2+ blockade

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24
Q

what do NMDAR act as

A

coincidence detectors after repetitive stimulation
permeate Ca2+ into the neurone - activates many secondary messengers

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25
Q

what is present on the GLUA2 sequence that codes for one of the glutamate receptor domains

A

codes for the reentrant loop
Q/R is present in the sequence
present in the pore lining
dictates permeability of the pore

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26
Q

what is the feature of GLUA2 lacking AMPAR

A

is Ca2+ permeable
inwardly rectifying conductance
high-single channel conductance
fast deactivation time

27
Q

what are TARPs

A

Transmembrane AMPAR Regulatory Proteins
different subtypes: gamma1-gamma8
y2 is known as stargazin
they effect trafficking and function

28
Q

what is necessary for the super-activation of glutamate receptors

A

the concerted action of L1 and L2 extracellular loops on TARPs

29
Q

what is the obligatory subunit of NMDA receptors for their expression

A

GluN1

30
Q

during development, which NMDA subunit is most prominent

A

GluN2B

31
Q

when does GluN2A expression increase

A

in adults

32
Q

what does Glun2B contain

A

a PDZ binding domain

33
Q

what is the function of a PDZ binding domain

A

binds to PSD-95 and promotes synaptic localisation

34
Q

for GABA receptors in maturing and adult physiology, what is the mM of Cl- inside and outside cell

A

outside - both 110mM
inside maturing - 30mM
inside adult - 5mM

35
Q

for GABA receptors in maturing and adult physiology, what voltage does the membrane want to rest at and why

A

adult = -82mV
maturing = - 34mV
caused by the distribution of Cl-

36
Q

what leads to the difference in internal Cl- mM from maturing to adult

A

KCC2 becomes more efficient at exporting Cl- to outside the cell as the physiology matures

37
Q

what are the features of GABA receptors

A

fast inhibition
tonic inhibition

38
Q

how many transmembrane domains do metabotropic receptors have

A

7

39
Q

what type of receptors are metabotropic receptors

A

Class C GPCR

40
Q

what is each subunit of metabotropic receptors made from

A

made from an extracellular venus fly trap domain (VFTD) that binds agonists and links to the 7 transmembrane domains

41
Q

what are mGlu receptors

A

homodimeric receptors - 2 metabotropic receptors

42
Q

what is required to form i dimer for mGlu formation

A

intramolecular disulfide bridges in both VFTDs

43
Q

what is required for mGluR activation

A

efficient signalling - glutamate binds to both VFTDs
can also activate from just one glutamate to one VFTD but less efficient

44
Q

which mGlu5R subtypes are more predominant during postnatal period and adulthodd

A

mGluR5a - postnatal period
mGluR5b - adulthood

45
Q

what is mGluR5

A

a group 1 receptor - mostly postsynaptic
can form homo/heterodimers

46
Q

what is the function of mGluR5

A

regulates mechanisms in neurogenesis and synaptic regulation

47
Q

what can disregulation of mGluR5 cause

A

Fragile X syndrome
autism
schizophrenia
Alzheimer’s

48
Q

what do distinct binding pockets of for NAMs in Glu1 and Glu5 reveal

A

that multiple sites in class C 7TMDs can bind allosteric regulators

49
Q

what can mGlu5 antagonists do

A

restore amyloid-beta inhibited LTP to normal levels

50
Q

what is the pathology of fragile X syndrom

A

mGlu5R activation is way too much
leads to way to much translation machinery being activated - transcribes mRNA into too many proteins that cause too much endocytosis of AMPA receptors - too few AMPA receptors are expressed on the surface

51
Q

what is the function of FMRP

A

inhibits translation machinery from transcribing mRNA - pivotal for preventing Fragile X syndrome

52
Q

what can GABAb receptors modulate

A

modulates the firing rate of basal ganglia neurons in the brain

53
Q

what is the structure of a GABAb receptor

A

GABAb1a - contains 2 N-terminal sushi domains (SD) - axonal localisation
GABAb1b - dendritic localisation

54
Q

what are the functions of the GABAb subunits

A

GABAb1a - contains the VFTD agonist binding site
GABAb1b - couples to the G-protein

55
Q

what are the functions of dopamine releasing neurones in the basal ganglia

A

steady, autonomous pacemaking
self-generated mechanism maintains extracellular dopamine levels

56
Q

how does GABA what can GABAb receptors form

A

supercomplexes - when heterodimers self-assemble into tetramers or oligomers

57
Q

how are supercomplexes formed

A

via interactions of the VFTD on GABAb1a

58
Q

what would happen if you applied a GABAb antagonist to dopamine releasing neurones in the basal ganglia

A

they inhibit it
the graph of activity goes silent

59
Q

what does GABAb lack

A

lacks a cysteine-rich domain - its more compact

60
Q

in terms of activation what is the difference between GABAb and mGlu heterodimers

A

GABAb only requires one agonist per dimer for full activation

61
Q

what are KCTDs

A

K+ channel tetramarisation domains
are GABAb receptor components that act as auxillary receptor subunits
they are not K+ channels
they help GABAb link with other proteins

62
Q

what are the core building blocks of GABAbR

A

GABAb1a
GABAb1b
KCTD
G-protein

63
Q
A

Biomed Season Finale (11 decks)

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