Receptors

Question 1

Excitatory ligand-gated channels

Answer 1

Most excitatory ligand-gated channels allow the flux of Na, K, and sometimes Ca

Question 2

Superfamilies of Vertebrate Ligand-gated Ion Channels:

Answer 2

• Pentameric Cys-loop Receptors (Nicotinic ACh, GABAa, Glycine) (5 subunits)
• Glutamate Receptors (AMPA-type, Kainate-type, NMDA-type) (4 subunits, 3 transmembrane helices) (permeable to sodium & potassium)
• ATP (P2X) receptors

Question 3

NMDA receptors

Answer 3

• NMDA receptor is usually blocked by a Mg2+ cap
• two events must happen for the receptor to open - binding of glutamate & change in membrane potential (depolarization, which pushes the Mg cap out)
• very permeable to Ca+, but also permeable to K & Na