Are Inactive Renins in Plasma and Kidney Related to Prorenin?

The availability of elegant studies examining in vitro RNA translation of renin's message, the cDNA sequence of mouse-renin messenger RNA, and the complete amino acid sequence of active renin reveals the biosynthetic pathway of this enzyme. This pathway proceeds in a series of steps that correspond to the common mode of synthesis of secreted proteins. This information must now be correlated with a profusion of observations concerning inactive forms of renin that are found in kidney and other tissues in far higher concentration than the active enzyme in human plasma. At this time, in spite of great efforts on the part of many laboratories, the connection between the inactive renins of tissue or plasma and renin's biosynthetic precursors is unknown. Furthermore, the physiologic and pathophysiologic roles that inactive renins play, if any, have not been defined.