Plant progesterone 5β-reductase is not homologous to the animal enzyme. Molecular evolutionary characterization of P5βR from Digitalis purpurea

P5βR, clone isolated from a Digitalis purpurea cDNA library, encodes the enzyme responsible of 5β-pregnane-3,20-dione formation in the cardenolide pathway. P5βR is not homologous to the animal enzyme.