The androgen receptor of the prostate plasma membrane - an hypothesis

The hypothesis that the prostatic plasma membrane sodium pump apparatus functions as a non-genomic androgen receptor is based upon a number of its properties: (1) Androgen enhances the uptake of K+ into minced rat prostate. (2) Ouabain, a specific inhibitor of Na/K-ATPase activity, strongly opposes the androgenic effect. (3) In non-genomic microsomes, ouabain sensitivity of the enzyme is enhanced by androgen. (4) Kinetic studies show that androgen significantly increases V-max, K-m and energy of activation of the enzyme. (5) Enzyme, treated with [gamma-P-32]-ATP and then subjected to SDS-PAGE etectrophoresis, binds only to its alpha-subunit, but, if treated with [H-3]-DHT, shows isotope binding to the beta-subunit. (6) [H-3]-ouabain binding to androgenized enzyme is 5.5 times greater than to the non-androgenized enzyme. (7) Treatment of the enzyme with 10(-9) M, DHT enhances by 40% the binding of the ouabain derivative, anthroyl, ouabain (AO). (8) Fluorescent spectra appears to show that, upon phosphorylation of the androgenized enzyme, there is a 14% approximation of the two subunits to each other. (9) Except for neuroepithelium, only the epithelium of the prostate has apically located Na/K-ATPase. Preliminary work in other tabs suggests that the P-subunit of the Na/K-ATPase may be required for establishing the polarity of some epithelial cells. (C) 2004 Elsevier Ltd. All rights reserved.