Has dehydrogenase activity against corticosterone (11 beta-hydroxysteroid) and estradiol (17 beta-hydroxysteroid) in the presence of NADP(+). May be involved in signal transduction regulated by various sterols. an 11beta-hydroxysteroid + NADP(+) = an 11-oxosteroid + H(+) + NADPH corticosterone + NADP(+) = 11-dehydrocorticosterone + H(+) + NADPH 17beta-estradiol + NADP(+) = estrone + H(+) + NADPH Surface of oil bodies. Exists at a monolayer lipid/water interface. Expressed in megagametophytes (at protein level). The proline-knob motif may be involved in the targeting to oil bodies. Belongs to the short-chain dehydrogenases/reductases (SDR) family.