Lec 15 Flashcards
Which of the 2 main types of glutamate ionotropic glutamate receptor is rarely permeable to Ca2+ ?
AMPA
Which of the 2 main types of glutamate ionotropic glutamate receptor is slower and highly permeant to Ca2+?
NMDA
Which of the 2 main types of glutamate ionotropic glutamate receptor mediates the great majority of fast excitatory transmission in the CNS?
AMPA
Which of the 2 main types of glutamate ionotropic glutamate receptor is important in neuronal plasticity?
NMDA
In either temporal or spatial summation, actions potentials from EPSPs are initiated in what region of the neuron?
axon hillock or initial segment
benzodiazepines and barbiturates affect which ligand channel?
GABAa
Which ligand receptor subunit has its M2 enter and exit the membrane region rather than passing through it?
glutamate
How many binding regions are located on a glutamate ionotropic receptor?
4
what 2 subunits can be reversed in a Nicotinic Ach receptor?
B and y.
Where are the binding regions for ACh located on a AChR?
on the alpha subunits
In a subunit within a ionotropic glutamate receptor , which transmembrane region (M1,M2,M3,or M4) is thought to enter and exit the membrane region rather than pass through?
M2 doesn’t pass through. (glutamate subunit = 3 passes)
How many binding regions are located on a glycine receptor ?
2 (a, B)
Defects in Glycine receptors can lead what disease?
startle disease (hyperekplexia)
What is defined as “an potential that is equal to the sum of multiple EPSP or IPSPs that are received at a postsynaptic NEURON at the same time in order to reach threshold and exhibit and action potential (or inhibit an AP in the case of IPSP)”
spatial summation
When studying ionotropic post synaptic glutamate receptors, if the postsynaptic membrane has a very low membrane potential which channel will open?
AMPA because it is independent of postsynaptic membrane potential NMDA will not for opposite reason.
In either Temporal or spatial summation, action potentials from EPSPs can only occur when the summed potential …
rises above the threshold.
EPSP’s are mediated by what type of anion or cation channels?
cation channels
EPPs (such as ACh release and binding to a postsynaptic membrane) are strongest at what location?
closer to the motor endplate or the presynaptic terminal.
How many TM regions are there in an ionotropic glutamate receptor?
4 subunits x 3TM per unit = 12 TM
Which of the 2 main types of glutamate ionotropic glutamate receptor is permeable to K+ and Na+ ?
AMPA and NMDA (both)
Oligopentamer channels/receptors came from a common ancestor . Over time, the structures split into two different catagories called:
Anion selective and Cation selective ligand gated channels
What drug will cause an increase in the Cl- conductance of an open GABAa channel ?
benzodiazepine
What type of ligand receptor contains binding region on its a only?
AChR
What are the 3 types of ionotropic glutamate receptors?
- AMPA-type subunits (GluR 1-4) 2. NMDA-type subunits (NMDAR 1, 2A-2D) 3. Kiante-type subunits (GluR 5&6 and KA1&2)
How many AMPA-type subunits are there in a glutamate ionotropic receptor?
4
What is the radial spacing of the subunits on an AChR? (in degrees)
72º
What are the 2 more important ligand gated anion channels?
Glycine and GABAa
GABAa channels can have their inhibitory effects increased by the addition of what substances?
barbiturates or benzodiazepines
How many subunits are in a glutamate ionotropic receptor?
4
What are the AMPA-type subunits in a glutamate ionotropic receptor?
GluR1, GluR2, GluR3, GluR4
at a NMJ or motor end plate, How is it possible to determine the selectivity or type of channel present on the postsynaptic membrane?
by voltage clamping the postsynaptic membrane and treating it with curare to create subthreshold responses and prevent APs, and recording the voltage-current relationship. By locating the reversal potential or nernst potential (where I=0), we an distinguish what type of channel is present.
What substance blocks GlyR?
strychnine
When studying ionotropic post synaptic glutamate receptors, if the postsynaptic membrane has a higher potential (-40mV) will Ca2+ flow into the postsynaptic membrane?
yes, due to the activation of NMDA as well as AMPA.
Which ligand channel comes from a different evolutionary line than the other ligand gated channels?
glutamate
Where is ACh synthesized?
cytoplasm
How long ago did the oligopentamer ligand gated channels first appear?
800 million years ago
What terminates the action of ACh in the synaptic cleft?
AChE - acetylcholinesterase
EPPs (such as ACh release and binding to a postsynaptic membrane) have a smaller delay when they are at what location?
closer to the motor endplate or the presynaptic terminal.
How many binding regions are located on a GABAa receptor?
3 (a1, B1,y2)
How many TM regions does the most ancient ligand channel have?
4 subunits x 3TM per unit = 12 TMs total (glutamate)
What are the 2 cation ligand receptors?
GABAaR and GlyR
By strictly adding benzodiazepine to a GABAa channel, without the presence of GABA, what will happen to the Cl- current?
The Cl- current will be unchanged without the presence of GABA.
What drug will cause an increase in the frequency of GABAa channel opening?
benzodiazepines (valium)