Lecture notes ligand-gated ion channel

exam Question :
Ligand-gated on channel
& Describe
* features/characteristics of Ligand-gatedion channel superfamily

↳ of conformational
binding ligand (neuro transmitter) =>
change in receptor protein =>
opening
of ion-permeable pore > flow of permeant ions

into/out of cell down their electrochemical gradient.
↳ in flow
through activated channel
= > modulation of cellular function.

↳ LGIs involved in wide range biological functions.

synaptic franission sh neural communications
e
g
.




cell excitation , muscle contraction s intracellular signalling.
question Describe
exam :



* basit for subclassification of
ligand-gated in channel families


↳
based on effect on membrane potential st cellular electrical

induced Channel
activity by ion flow
through open




* Excitatory ,
cation-selective LGIs => nAChR ,
S-HTzR

ionotropic glutamate (NMDA ,
AMPA & Kainate) receptors
& P2X receptors·
Mediate influx of cation= > membrane depolarisation


* inhibitory ,
anion-selective LGI +=> GABAAR$
glycine receptors exam question : Describe
↳ characteristic feature of major
- Mediate influx of anion
= > Membrane
hyperpolarisation .
Key
channel families
Ligand-gated ion



I
cys-loop Receptor family
-



pentameric :
composed of S subunits
- nAChR , S-HTsR , GABAAR ,
glycine receptors

-
Conotropic Glutamate Receptor family
Tetrameric
- composed : of 4 submit

-
NMDA ,
AMPA & Kainate receptor

③ 2X Receptor family
-
Trimeric :
composed of 3 subunits

-
P2x1 ,
P2X2 , P2X3 , P2X4 ,
P2X5 & P2X7

receptors