How many domains do ligand-gated ion channels frequently consist of?

How many membrane-spanning helices does each subunit of a ligand-gated ion channel typically consist of?

What makes a ligand-gated ion channel 'closed'?

How do transmembrane helices making up the subunits of ligand-gated ion channels determine the selectivity of the ion channel?

What is the first step in signal transduction involving cAMP generation?

After a ligand has bound to its appropriate G-protein coupled receptor, there is a conformational change to the receptor. What does this do?

What happens to the G protein when it is able to bind to the receptor?

What happens to the G protein when GTP has bound to it?

What determines whether the binding of the ligand to the receptor will have stimulately or inhibitory intracellular signalling effects?

What effect does the alpha-s subunit have?

What effect does the alpha-i subunit have?

What effect does the alpha-o subunit have?

What effect does the alpha-q subunit have?

What does adenylate cyclase do?

Why is activation of adenylate cyclase by the alpha-s subunit self-limiting?

What are the possible intracellular effects that result from cAMP production?