Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Molecular and Cellular Neuroscience > GABA and Glycine Receptors > Flashcards

GABA and Glycine Receptors Flashcards

(55 cards)

Start Studying
1
Q

What does GABA stand for?

A

Gamma aminobutyric acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What type of neurotransmitters are gaba and glycine?

A

Inhibitory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the precursor aminoacid for glycine?

A

Serine

Converted to glycine by serine hydroxymethyl transferase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What enzymes converts glutamate in GABA?

A

Glutamic acid decarboxylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the types of GABA receptors?

A

GABAa (ionotropic anions)
GABAb (metabotropic Gi linked)
GABAc (ionotropic found in retina)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What family of receptors are glycine and GABAa in?

A

Cys-loop receptors

As well as nAchR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does a subunit of a GABAa look like?

A 
Extracellular N (ligand blinding)
TM1
TM2
TM3
(Large intracellular loop site of phosphorylation to regulate channel properties)
TM4
Extracellular c terminus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How many subunits come together for from a glycine and GABAa receptor?

A

5 (pentamers)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Glycine subunit pattern?

A

Alpha - beta - alpha - alpha - beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

GABAa receptors are typical formed from what subunits?

A

2 x alpha (same subtype)
2 x beta (same subtype)
1 x gamma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How many GABAa alpha subtypes exist?

A

6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How many GABAa beta subtypes exist?

A

4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How many GABAa gamma subtypes exist?

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where does GABA bind to in GABAa receptors?

A

The interface between the alpha and beta subunit

Therefore 2 GABA molecules are needed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Benzodiazepines are a positive allosteric modulator for the GABAa receptors…what subunits are required for BDZ to bind?

A

Alpha (1,2,3,5)
Gamma (2)

Bind between the alpha and gamma subunit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What percentage homologous exists between subunits in same group?

A

Approx 70%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What percentage homology exists between different gabaa subtype groups?

A

30%-40%

Alpha and gamma more closely related than alpha and beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Subtypes of GABAa receptors can be found through many areas of the brain.
Give 2 examples

A

Hippocampus - alpha 1 and 5

Cerebellum (granule cells) - alpha 6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Most common beta subunits expressed in brain?

A

(Beta 2 and 3) > beta 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Most common gamma subunits?

A

2>1>3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why is subunit diversity important?

A

Different channel kinectics
Differently regulated and vary modulators effects
Different affinity got agonist
Different channel properties
Different locations - targeted to different regions of the cell
Different pharmacology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What amino acid at what position is essential for bdz binding?
What amino acid do alpha 4 and 6 have in the same position?
How can this knowledge be used to study BDZs?

A

Histidine at position 101 on alpha subunits 1,2,3 and 5
Alpha 4 and 6 have an arginine
Knock in mutations replacing the histidine for a different amino acid (arginine) allow for the function of bdz working on that particular subunit to be studied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the function of BDZs at the alpha 1 subunit responsible for?

Study These Flashcards
A

Sedation

Anticonvulsant

24
Q

What is the function of BDZs at the alpha 2 subunit responsible for?

25
40% of GABAa receptors have these subunits
2xalpha1 2xbeta2 1xGamma 2
26
Name some GABAa agonists
Gaba Muscimol B-alanine
27
Name some glycine receptor agonists
Glycine Taurine B-alanine
28
Name some GABAa antagonists
Bicuculline (competitive) Picrotoxin (non competitive) H+
29
Name a glycine receptor antagonist
Picrotoxin (non competitive)
30
Why is the beta subunit important for glycine receptors?
Intracellular binding to scaffolds and receptor targeting
31
What protein binds to one of the beta subunits of two glycine receptors?
Gephyrin
32
What is gephyrin and how is it important?
93kDa protein P1 isoform interacts with beta subunit of glycine receptors May be present with other without glycine receptors Believed to have many functions but distribution of glycine receptors is one of them
33
In terms of activation, desensitisation and deactivation describe which is faster
``` Activation = GABAa (0.7ms)>glycine(1.3ms) Deactivation = GABAa>glycine Desensitisation = GABAa>glycine ```
34
What is the EC50 and hill slope of glycine receptor dose responce curve for glycine?
EC50=54 (micro)M | Hillslope = 1.6
35
What is the EC50 and hillslope for GABAa receptors for GABA?
``` EC50 = 45(micro)M Hillslope = 1.1 ``` Measured in cerebellar purkinje cell
36
What does an upwards and downwards deflection on a current graph thing mean for GABAa receptors?
Upward current means chloride ions moving in | Downwards current means chloride ions moving out
37
If extracellular concentration of Cl- = 140mM And intracellular concentration is 6mM What is the estimated equilibrium potential?
-84.2mV meaning at RMP chloride ions will move in
38
What is the actual equilibrium potential for a GABAa receptor?
About -70mV
39
Why is there a difference in equilibrium potentials between chloride and GABAa?
GABAa receptors also permeable to bicarbonate ions
40
What is the extra and intracellular concentration of bicarbonate and what is the equilibrium potential?
``` Out = 20-30mM In= 10-20 mM E = -10mV ``` Meaning at RMP ions will move out
41
If RMP is -70mV and equilibrium potential for GABAa is -70mV, what will happen on application of GABA.
Membrane potential will remain the same Chloride ions will move in (towards is EP), bicarbonate ions moving out (towards it EP) will balance the movement of charge (electroneural) However, since bicarbonate will leave its associative H+ will remain in cell therefore ph will drop on GABA application
42
What is the difference in chloride concentrations between mature and developing neurons?
Mature = low intracellular concs Immature = high mature neurons have KCC2 channels which export 2 Chloride ions
43
What scientist discovered that kcc2 expression changes with age?
Rivera et al 1999 Used northern blotting of rat hippocampi of different ages Shows KCC2 expression increases over time
44
What technique allows for intracellular chloride to be measured?
Gramicidin perforated patch | Inserts monovalent action channels into membrane which allows measurement of current
45
What cannot traditional whole cell patch clamp be used to measure intracellular chloride?
Pipette content will enter the cell and disrupt true intracellular chloride concentration (prevents accurate recording)
46
Gramicidin allows for true intracellular chloride to be measured...how?
By not dializing the cell the true chloride conc remains within the cell. Create the voltage current relationship to find equilibrium potential. If we then know the extracellular concentration of chloride (which is a variable we have set) we can use the nernst equation to work out intracellular conc
47
What are the implications of varying intracellular chloride concentration?
Will effect direction current will flow E.g. With gramicidin current at -50mV is upward deflection Without gramicidin intracellular concentration of chloride increases and for the same voltage step it is a downward deflection
48
What will be the equilibrium potential for GABAa in a developing neuron? What are the implications if this?
Higher than that of a mature neuron (-34mV) Therefore, GABA application in a developing neuron may be excitatory At voltages between the equilibrium potentials of a mature and immature neuron Mature neurons will hyperpolarise Immature will depolarise
49
What term describes how both stimulatory and inhibitory inouts come together at the axon hillock to dictates if an action potential fires?
Neuronal intergration
50
What is special about the axon hillock?
High density of VG sodium channels lowers the threshold for action potential firing
51
What factors influence the extent of neuronal integration?
Amplitude Proximity Location size/shape of synapse
52
What is the effect of an inhibitory synapse more proximal to the cell body than an excitatory synapse?
GABA will open chloride channels Will causes greater electrical shunting Will decrease the EPSP (Lowe the chance of action potential firing) Postive charge will be cancelled out by negative chloride ions
53
What will the effect of GABA be in developing neurons?
It may be excitatory and may induce and action potential alone for potentate excitatory glutamate EPSPs
54
In developing neurons what concentration of intracellular Cl-?
Up to 40mM
55
In mature neurons what is the intracellular concentration of Cl-?
4-10mM

Molecular and Cellular Neuroscience (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions