Steroid hormone specifically binds to rat kidney plasma membrane

A high-affinity and low-capacity corticosterone specific binding was detected in the purified plasma membrane preparation from rat kidney using anin vitro steroid hormone binding assay. The specific-bound hormone was efficiently distinguished from the irreversible-bound hormone with 10 µM corticosterone. Under standardized conditions of pH 7.4 at 2°C and 30 min incubation time, the binding was saturable and showedK _d=13±3 nM andB _max=616±34 fmol/mg of protein. Competitive binding studies with analogue steroids indicated that corticosterone binding to kidney plasma membrane is hormone-specific. Results indicated that the possible nongenomic effects of steroids could be mediated by their interaction with plasma membrane.