Abstract
Testosterone (T) and dihydrotestosterone (DHT) were found to bind to a specific protein in foreskin fibroblasts of a male pseudohermaphrodite with 5α-reductase deficiency. While maximum number of binding sites (B max) were similar for both androgens, the apparent dissociation constant (Kd) of the androgen receptor for T was greater than for DHT. In competition studies of 3H-T bound to the receptor with unlabeled T or DHT, the inhibitor constant (Ki) for T was two to three fold greater than the Kj for DHT. Also, the dissociation rate constant (kd) for 3H-T bound to the receptor was greater than for 3H-DHT (t 1/2 for T = 10 h and t 1/2 for DHT = 74.5 h).
These results suggest that T may play a role in the sexual differentiation of patients with 5α-reductase deficiency. Their incomplete masculinization would be explained by the lower affinity and faster turnover rate of the T-receptor complex relative to the DHT-receptor complex.
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Maes, M., Sultan, C., Zerhouni, N. et al. Binding properties of androgen receptors in genital skin fibroblasts of a patient with 5α-reductase deficiency. Pediatr Res 13, 1189 (1979). https://doi.org/10.1203/00006450-197910000-00052
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DOI: https://doi.org/10.1203/00006450-197910000-00052