Effects of proteases and protease inhibitors on the 4.5 S and 8 S androgen receptor.
The size of androgen receptors from rat ventral and dorsal prostate, dorsal prostate (Dunning) tumor, testis, epididymis, and seminal vesicle was determined using Sephadex G-200 chromatogrpahy and sucrose gradient centrifugation. The protease inhibitor diisopropyl fluorophosphate (DFP) was used to minimize receptor breakdown. An 8-9 S, 85 to 106 A receptor (Mr = 280,000 to 365,000; f/fo = 1.9 to 2.4) observed in unfractionated cytosol prepared in low ionic strength buffer with or without DFP is in equilibrium with a 4.5-5 S, 58 A form (Mr = 117,000; f/fo = 1.8) observed at salt concentrations greater than 0.1 M KCl. Receptor partially purified using (NH4)2SO4 or phosphocellulose chromatography in the absence of DFP was present as smaller fragments of 3.6 S, 37 A and 3.0 S, 23 A. Similar fragments could be generated from the 4.5 S or 8 S receptor by mild trypsin treatment. In addition, ventral prostate contains a DFP-insensitive enzyme which specifically converts the 4.5 S, 58 A receptor to the 3.6 S 37 A fragment. The DFP-insensitive enzyme is partially inhibited by rabbit bile and appears similar to the enzyme seminin, a secretory protein of human prostate. Androgen receptor isolated in the presence of DFP from nuclei labeled in vivo is predominantly 4.5 S, 58 A, with smaller forms (37 and 23 A) appearing in the absence of DFP. The 4.5 S, 58 A nuclear receptors were also in equilibrium with a large 8 S form. Receptor breakdown by DFP-insensitive and sensitive proteases appears to be an in vitro phenomenon. Furthermore, the size of the androgen receptor is not significantly changed during receptor migration from cytoplasm to nucleus.
D000818:Animals; D003600:Cytosol / Q000378:metabolism; D013196:Dihydrotestosterone / Q000378:metabolism; D004822:Epididymis / Q000378:metabolism; D007531:Isoflurophate / Q000494:pharmacology*; D008297:Male; D008970:Molecular Weight; D011467:Prostate / Q000378:metabolism; D051381:Rats; D011944:Receptors, Androgen / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*; D012669:Seminal Vesicles / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D013737:Testis / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism; D014357:Trypsin / Q000494:pharmacology*
D011944:Receptors, Androgen; D011987:Receptors, Steroid; D013196:Dihydrotestosterone; D007531:Isoflurophate; D013739:Testosterone; D014357:Trypsin