Solubilization of rat kidney plasma membrane proteins associated with 3H-aldosterone

The treatment of rat kidney plasma membranes with sodium dodecyl sulphate (SDS) did not essentially affect the ability of the membranes for 3H-aldosterone binding as compared with the intact plasma membranes (Ozegović et al., 1977). A gel filtration of 3H-aldosterone-kidney plasma membranes complex on Sepharose 6B yielded 2 protein and 2 3H-aldosterone peaks. The proteins which were eluted in the first peak were associated with the first 3H-aldosterone peak while the second 3H-aldosterone peak was eluted with Ve corresponding to Ve of free 3H-aldosterone. Spironolactone, a competitive antagonist of aldosterone, prevented the binding of 3H-aldosterone to the membrane proteins. The results demonstrated a high affinity of the kidney plasma membranes solubilized with SDS and a specificity of aldosterone binding to the plasma membrane proteins of higher molecular mass.