The diagram below illustrates the cellular mechanism of action of antidiuretic hormone (ADH) in the epithelial cells of the kidney's collecting duct.
Which of the following describes the correct sequence of events occurring in these cells in response to an increase in blood ADH concentration?
ADH binds to specific receptors on the basolateral membrane, activating adenyl cyclase to produce cyclic AMP (cAMP\text{cAMP}cAMP). This activates protein kinase A, causing vesicles containing aquaporins to fuse with the apical membrane.
ADH binds to specific receptors on the apical membrane, activating adenyl cyclase to produce cyclic AMP (cAMP\text{cAMP}cAMP). This activates protein kinase A, causing vesicles containing aquaporins to fuse with the basolateral membrane.
ADH passes directly through the phospholipid bilayer of the basolateral membrane, binding to intracellular receptors to initiate transcription of the gene encoding aquaporin-2 channels.
ADH binds to specific receptors on the basolateral membrane, opening ligand-gated calcium channels to allow calcium ions to diffuse into the cell and directly open existing aquaporin channels.