G protein-coupled receptors (GPCRs) activate by
- A
Binding ligand, opening an ion channel, which then permits direct flow of calcium ions
- B
Binding ligand, dimerizing with a partner receptor, which then activates nuclear transcription
- C
Binding ligand, autophosphorylating tyrosine residues, which then create docking sites
- Dcheck_circle
Binding ligand, activating an associated G protein, which then activates downstream effectors
Explanation
Ligand binding triggers GDP→GTP exchange on the G protein α subunit; activated Gα regulates effectors like adenylyl cyclase.