Can convert androstan-3-alpha,17-beta-diol (3-alpha-diol) to androsterone in vitro, suggesting that it may participate in androgen metabolism during steroidogenesis. May act by metabolizing compounds that stimulate steroid synthesis and/or by generating metabolites that inhibit it. Has no activity toward DHEA (dehydroepiandrosterone), or A-dione (4-androste-3,17-dione), and only a slight activity toward testosterone to A-dione. Tumor-associated antigen in cutaneous T-cell lymphoma. 17beta-estradiol + NAD(+) = estrone + H(+) + NADH 17beta-estradiol + NADP(+) = estrone + H(+) + NADPH Redistributed from the endoplasmic reticulum to lipids droplets in the cell upon induction of lipids droplet formation. Present at high level in steroidogenic cells such as syncytiotrophoblasts, sebaceous gland, Leydig cells, and granulosa cells of the dominant follicle and corpus luteum. In lung, it is detected in the ciliated epithelium and in acini of adult trachea, in bronchioles, but not in alveoli. In the eye, it is detected in the nonpigmented epithelium of the ciliary body and, at lower level, in the inner nuclear layer of the retina (at protein level). Widely expressed. Highly expressed in retina, pancreas, kidney, liver, lung, adrenal, small intestine, ovary and heart. Belongs to the short-chain dehydrogenases/reductases (SDR) family. 17-beta-HSD 3 subfamily.