Responsible for the reduction of the keto group on the C-3 of sterols. a 3beta-hydroxysteroid + NADP(+) = a 3-oxosteroid + H(+) + NADPH Steroid biosynthesis; zymosterol biosynthesis; zymosterol from lanosterol: step 5/6. Belongs to the short-chain dehydrogenases/reductases (SDR) family. ERG27 subfamily.