. "\"Catalysis of the reaction: (E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate + NAD(P)H + H+ = isopentenyl diphosphate + NAD(P)+ + H2O. Note that (E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate is an alternative name for 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate.\" [EC:1.17.1.2]" . . "4-hydroxy-3-methylbut-2-en-1-yl diphosphate reductase activity" . "4-hydroxy-3-methylbut-2-enyl diphosphate reductase activity" . "isopentenyl-diphosphate:NAD(P)+ oxidoreductase activity" . "EC:1.17.1.2" . "MetaCyc:ISPH2-RXN" . .