ligand gated ion channel receptors & G-protein coupled receptors Flashcards
what do channel proteins form?
water filled pores
how is the opening and closing of ion channels regulated?
voltage / ligands
how do ligand gated ion channels work?
These are transmembrane water-filled channels which can be opened or closed by the binding of the relevant ligand to the receptor
what happens when the ligand binds?
the ion channel opens and the ion flows
are all ion channels specific?
some are specific, only allowing one type of ion to flow through, others are not
what are cationic channels used for?
Na+, Ca++,K+ , they are usually excitory and often lead to depolarisation. They let anything with a positive charge flow through
give an example of cationic channel
nicotinic acetyl choline receptor which works as a Na+ channel
how do anionic channel work?
they are for Cl- generally, they exert inhibitory (hyperpolarisation) effects once opened
what does selectivity of ion channels depend on?
the diameter of the trans membrane channel and the amino acids that line the channel
where are nicotinic receptors found
at neuromuscular junctions. they play an important role in allowing muscles to move
how many subunits are in the nicotinic acetyl choline receptor?
5 subunits, 2 of which are alpha
where do the ion pass through in the nicotinic acetyl choline receptor?
the central pore
what ions does GABBA receptor allow to go through?
Cl-
how many molecules of acetylcholine bind to open the ion? and where do they bind?
2 molecules, they bind between the alpha and the gamma, causing a conformational change which allows the subunits to rotate and open up.
what effect does Curare (tubocurarine), the plant have on acetylcohline? how does it do this?
the poison functions by inhibiting the nicotinic acetylcholine receptor, which is found at the neuromuscular junction. the poison causes weakness of the skeletal muscles and at high dose, eventually death, due to paralysis of the diaphragm and cessation of breathing
