4-hydroxy-3-methylbut-2-enyl diphosphate reductase

4-hydroxy-3-methylbut-2-enyl diphosphate reductase (or HMB-PP reductase) is an enzyme in the non-mevalonate pathway.

It acts upon (E)-4-Hydroxy-3-methyl-but-2-enyl pyrophosphate (or "HMP-PP").

It is classified under EC 1.17.1.2.