Influence of Ca2+ and pH on the folding of the prourotensin II precursor

► Prourotensin II is stably folded in acidic buffers containing calcium. ► The proprotein convertases (PC1 and PC2) cleave urotensin II from its precursor. ► Conditions for stable folding coincide with those for optimal cleavage of prourotensin II. ► Stable folding of precursor and optimal cleavage conditions facilitate efficient processing.