lec 8. ligand gated ion channels

Question 1

receptors

Answer 1

usually cell surface proteins that bind ligands and cause response

Question 2

ion channels

Answer 2

allow flow of ions to change intracellular ion concentration

Question 3

features of ion channels

Answer 3

ion selectivity - define by physical size of pore (P-loop) and amino acids lining it

gated mechanism - ligand gated or voltage gated

Question 4

pore domain

Answer 4

S5, P-loop, S6

Question 5

Kv1 channel

Answer 5

4 subunits, 6 TMDS (S1-S6)

voltage gated channel - depolarisation causes S4 to pull S5 open, allowing K+ through

Question 6

Cyclic nucleotide gated channel

Answer 6

• similar to Kv with additional regulatory domains

binding of cAMP or cGMP opens channel allowing Na+ and Ca+ through, Ca+ binds to N-terminal providing negative feedback

Question 7

P2X Receptor

Answer 7

• ionotropic ligand gated ion channel
• 3 subunits, 2 TMDs
• gated by binding of ATP to extracellular pocket

Question 8

Glutamate Type Receptor

Answer 8

• 4 subunits, 3 TMDs (dimer of dimers)
• S5, P-loop (flipped), S6 + amino acid binding protein
  binds glutamate, M1 M2 M3 pull channel open, allowing K+ Na+ and sometimes Ca+ through

EX. NMDA, Kainate, AMPA

Question 9

Cys-loop Receptors

Answer 9

• 5 subunits, 4 TMDs
• Bind ATP, M2 rotates to open pore, allows Na+ K+ Ca+ through (controlled by amino acids). GABA lets Cl- through

EX. nAChR, GABAr