title: Different ionic forms of estrogen receptor in rat uterus and human breast carcinoma.
abstract: Estrogen receptors from rat uterus and human breast carcinoma were analyzed by diethylaminoethyl-cellulose chromatography. Cytosols which had been incubated for short periods of time demonstrated a single discrete elution peak, indicating a single ionic form, while cytosols incubated for longer periods of time generated a second ionic form of receptor. Addition of cations to cytosols also promoted the rapid appearance of this second ionic form of receptor. Either leupeptin, a protease inhibitor, or sodium molybdate prevented the appearance of this second ionic form of estrogen receptor. The estrogen receptor from rat uterine cytosol incubated without leupeptin or molybdate had a smaller apparent molecular weight than did estrogen receptor from cytosols incubated with leupeptin or molybdate. Altogether, these experiments suggested that a cation-dependent protease present in the cytosols from both tissues was degrading the estrogen receptor to a second smaller species during extended incubation times.
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism*; D002848:Chromatography, DEAE-Cellulose; D003600:Cytosol / Q000378:metabolism; D005260:Female; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D046911:Macromolecular Substances; D008970:Molecular Weight; D011487:Protein Conformation; D051381:Rats; D011960:Receptors, Estrogen / Q000378:metabolism*; D012492:Salts; D014599:Uterus / Q000378:metabolism*
chemical_list: D007976:Leupeptins; D046911:Macromolecular Substances; D011960:Receptors, Estrogen; D012492:Salts