- Proprotein conversion is determined by a multiplicity of factors including convertase processing, substrate specificity, and intracellular environment. Cell type-specific processing of human prorenin by the convertase PC1. Benjannet, S., Reudelhuber, T., Mercure, C., Rondeau, N., Chrétien, M., Seidah, N.G. J. Biol. Chem. (1992)