Regulation of CYP17A1 activity and its potential implications on the development of boar taint

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Billen, Machteld Joanna

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University of Guelph


Testicular 16-androstene steroids, in particular 5[alpha]-androstenone, contribute to an off-odour and off-flavour known as boar taint. Cytochrome P450 C17 (CYP17A1) catalyses the key regulatory step in the formation of the 16-androstene steroids from pregnenolone via the andien-[beta] synthase reaction, or the synthesis of the glucocorticoid and sex steroids via 17[alpha]-hydroxylase and C17,20 lyase pathways respectively. The goals of this research were to investigate the effect of both isoforms of CYB5 and the phosphorylation status of CYP17A1 on these different activities of CYP17A1, by overexpressing these proteins in HEK-293 cells. CYB5A increased andien-[beta] synthase and C17,20 lyase activities while CYB5B increased C17,20 lyase but had no effect on andien-[beta] synthase activity. Phosphorylation of CYP17A1 at Ser 106 in the presence of CYB5A increased C17,20 lyase and andien-[beta] synthase activity. This suggests that decreased expression of CYB5A and increased expression of CYB5B would maintain sex steroid production and decrease boar taint. Key Words: CYP17A1, CYB5, Androstenone, C17, 20 lyase, 17[alpha]-hydroxylase



Boar taint, Steroids, 16-androstene, CYP17A1, Pregnenolone