Ligands & receptors
Types of receptors
Ligand-gated ion channels
G protein-coupled receptors
- When a signaling molecule binds to the GPCR, the G protein alpha subunit exchanges GDP for GTP.
- The alpha subunit dissociates from the beta and gamma subunits and interacts with other molecules, ultimately triggering a cellular response. (The beta and gamma subunits may, in some cases, also participate in signaling.)
- GTP is hydrolyzed to GDP, and the signaling molecule comes off of the receptor.
- The alpha subunit comes back together with the receptor and the beta and gamma subunits.