Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study reports the specificity, kinetics and thermodynamics of the binding of tritiated testosterone to specific receptors in the cytosol of the hypothalamic-preoptic area of the adult male mouse brain. Values for the kinetic is parametrs KA, KD, ka, kd and the apparent free energy (delta GOoc) are reported. The specificity of these receptors was investigated by LH-20 chromatography and sucrose-gradient centrifugation. Differences inreceptor specificity between the mouse and that reported for the rat are described. The effects of the antiandrogens, cyproterone acetate and BOMT, and the anti-estrogens MER-25 and clomiphene citrate on the binding of tritiated testosterone to specific 8S receptors are also reported. The effect of these steroid receptor antagonists on testosterone binding is discussed in relation to the current theory on the mechanism by which androgens influence brain function.
Steroids 1979 Apr
PMID:Binding properties of testosterone receptors in the hypothalamic-preoptic area of the adult male mouse brain. 44 32

Aromatase from human placenta has been purified to homogeneity (MW 55,000). Enzymatic activity can be reconstituted with reductase from pig liver in an aqueous buffer or after incorporation of the enzyme into liposomes. In both cases the enzyme converts androstenedione to estrone and testosterone to estradiol. Aromatase shows a typical CO-spectrum when reduced with dithionite and a type I spectral shift with both substrates. The NH2 terminal amino acid sequence is hydrophobic but shows no homology to that of other cytochromes P-450. Five cysteine peptides have been isolated by HPLC following tryptic digestion of the [14C]-carboxymethylated protein. Amino acid sequences of these peptides reveal that histidine is the carboxy-terminal amino acid of the protein and that significant homology exists with corresponding peptides from other cytochromes P-450. Unique oligonucleotides (62 and 30 MER) synthesized on the basis of a 45 amino acid sequence near the center of the molecular have been used to clone the aromatase gene from a cDNA expression library from human placenta in lambda gt11.
Steroids
PMID:Purification and characterization of aromatase from human placenta. 350 67

Rat skeletal muscle cytosol proteins bound 3H-diethylstilbestrol (3H-DES). More than 90% of this binding was high capacity and low affinity. Serum albumin accounted for roughly 50-60% of the binding, as evidenced by its precipitation with anti-rat albumin IgG. About half of the binding was distinguishable from albumin and other serum proteins by its precipitation in 40% saturated ammonium sulfate. This material sedimented at 4-5S in high-salt sucrose gradients, and resolved into two components (8S and 4-5S) in low-salt. Following incubation at 23-27 degree C for one hour, 2% of the bound 3H-DES in whole cytosol (approximately 2 fmole/Mg cytosol protein) was retained by DNA cellulose, and was eluted with 0.6 M KCl. This small fraction of the total binding was inhibited by estrogens and DES analogues: estradiol-17 beta, DES, dienestrol, and hexestrol were strong inhibitors; isodienestrol, dimethylstilbestrol, estradiol-17 alpha, estrone, tamoxifen, MER-25, CI-628, and nafoxidine were weak inhibitors; dihydrotestosterone, testosterone, and prednisone did not compete. These observations indicate that specific estrogen-binding sites exist in rat skeletal muscle.
Steroids 1982 May
PMID:Specific cytosol binding of diethylstilbestrol in rat skeletal muscle. 675 12

5 alpha-Dihydrotestosterone, 17-hydroxyprogesterone caproate, 2-methoxyestrone and a number of nonsteroidal antiestrogens (clomiphene citrate, nafoxidine hydrochloride, tamoxifen, MER-25) were tested for their ability to block estradiol-mediated repression of the androgen-dependent 3 beta-hydroxysteroid dehydrogenase activity of male rat liver. With the exception of 5 alpha-dihydrotestosterone, which induced activity in females, none of these substances affected 3 beta-hydroxysteroid dehydrogenase activity when administered alone to otherwise untreated male and female rats. Tamoxifen (100 or 500 micrograms/day) was the only substance which prevented a decrease in enzyme activity when given simultaneously with estradiol (5 micrograms/day). The estradiol-mediated decrease in activity was not antagonized by a 100-fold higher dose of androgen (5 alpha-dihydrotestosterone, 0.5 mg/day), demonstrating the potent antiandrogenic effect of estradiol on this hepatic androgen-dependent enzyme activity.
Steroids 1980 Nov
PMID:Antagonism of the estradiol-mediated repression of microsomal 3 beta-hydroxysteroid dehydrogenase activity in rat liver by antiestrogenic substances. 693 24