Fig. 2.

Principal pathways of human steroid biosynthesis. Pathways for biosynthesis of progesterone, mineralocorticoids, glucocorticoids, androgens, and estrogens. Names of the enzymes that catalyze each step are indicated in boxes. 17-OH Preg, 17-Hydroxypregnenolone; 17-OH Prog, 17-hydroxyprogesterone. *, 11-Deoxycorticosterone is converted to corticosterone by 11-hydroxylase activity of CYP11B2 (in zona glomerulosa) or by CYP11B1 (in zona fasciculata). #, The conversion of 17-hydroxyprogesterone to androstenedione by CYP17 is limited in humans.