A) is a water-insoluble messenger molecule.
B) binds to the calcium channel of the endoplasmic recticulum.
C) is involved in the release of calcium into the cytosol.
D) is a second messenger that is involved in the release of calcium into the cytosol.
E) uses all of the mechanisms.

A) a G protein.
B) adenylyl cyclase.
C) protein hormones.
D) protein kinase A.
E) hormone receptors.

A) only increase its number of receptors for a ligand.
B) only decrease its number of receptors for a ligand.
C) only increase its binding affinity for a ligand.
D) decrease the receptors' binding affinity and increase its number of receptors.