L3 - Excitation Flashcards
2 examples of A.acid excitatory and inhibitory NT (small molecule NTs)
E: Glutamate, aspartate
I: GABA, Glycine
Difference b/n 4-trans and 3-transmembrane helices
Location of N and C terminus.
- 3-trans (N extra, C intra)
- 4-trans (Extracellular)
3-Trans also tends to have a pore loop (N2 loop).
What type of transmembrane subunits make up AMPA receptors?
3 transmembrane helices
Function of amino terminus domain
Involved in desensitisation and modulation. Without it = excited toxicity due to sustained depol. leading to sustained accumulation of intra. Ca2+
R/ship b/n glutamate and GABA
Glutamate -(lose one -COO-)-> GABA
Difference b/n glutamate and glutamine
Glutamine has an extra -NH2 group on the end, hence COO- is C=0 and can’t bind to GluR
How is glutamate recycled?
Exits via presynaptic terminal. Reuptake via EATT where Glutamate -> Glutmaine using Glutamine synthease in the glial cell. Exits glial cell and ready for reuptake via presynaptic terminal and converted to Glutamate via Glutaminase.
What does an NMDA recceptor need to have an effect?
Glutamate and depol. dependent. If you only have one but not the other, nothing will happen. This is due to the Mg2+ blocking the ion channel, hence requires depol. so it will move out of the way.
p.s. it transmits more Ca2+ than AMPA and kainate receptors which can act as second messenger within cell
Compare duration of response for AMPA and NMDA receptors.
AMPA - Short
NMDA - Long
ACh receptor - subunits for muscle and neuronal? How many alpha do you always need and why?
5 subunits, 4-transmembrane spanning domains
Muscle - 2 alpha, 3 others
Neuronal - 3 alpha, 2 beta
Needs 2 alpha as alpha is a binding pocket for ACh
NT inactivation for ACh
ACh esterase in the synaptic cleft breaks it down in acetate and choline where choline is reuptaken into the presynaptic terminal and converted into ACh again.
