Characterization of R5020 and RU486 binding to progesterone receptor from calf uterus

Journal Article · Tue May 17 00:00:00 EDT 1988 · Biochemistry; (United States)

OSTI ID:7191999

Hurd, C; Moudgil, V K

The authors have examined and compared the binding characteristics of the progesterone agonist R5020 (promegestrone, 17,21-dimethylpregna-4,9(10)-diene-3,20-dione) and the progesterone antagonist RU486 (mifepristone, 17..beta..-hydroxy-11..beta..-(4-(dimethylamino)phenyl)-17..cap alpha..-(prop-1-ynyl)-estra-4,9-dien-3-one) in calf uterine cytosol. Both steroids bound cytosol macromolecule(s) with high affinity, exhibiting K/sub d/ values of 5.6 and 3.6 nM for R5020 and RU486 binding, respectively. The binding of the steroids to the macromolecule(s) was rapid at 4/sup 0/C, showing saturation of binding sites at 1-2 h for (/sup 3/H)progesterone and 2-4 h for both (/sup 3/H)R5020 and (/sup 3/H)RU486. Addition of molybdate and glycerol to cytosol increased the extent of (/sup 3/H)R5020 binding. The extent of (/sup 3/H)RU486 binding remained unchanged in the presence of molybdate, whereas glycerol had an inhibitory effect. Molybdate alone or in combination with glycerol stabilized the (/sup 3/H)R5020- and (/sup 3/H)RU486-receptor complexes at 37/sup 0/C. Competitive steroid binding analysis revealed that (/sup 3/H)progesterone, (/sup 3/H)R5020, and (/sup 3/H)RU486 compete for the same site(s) in the uterine cytosol, suggesting that all three bind to the progesterone receptor (PR). Sedimentation rate analysis showed that both steroids were bound to a molecule that sediments in the 8S region. The 8S (/sup 3/H)R5020 and (/sup 3/H)RU486 peaks were abolished by excess radioinert progesterone, RU486, or R5020. The results of this study suggest that, although there are some differences in the nature of their interaction with the PR, both R5020 and RU486 bind to the same 8S receptor in calf uterine cytosol.

• Research Organization: Oakland Univ., Rochester, MI (USA)
• OSTI ID: 7191999
• Journal Information: Biochemistry; (United States), Vol. 27:10
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PROGESTERONE
BIOCHEMICAL REACTION KINETICS
CONFIGURATION INTERACTION
RECEPTORS
TRITIUM COMPOUNDS
ATP
CALVES
MOLYBDATES
UTERUS
ANIMALS
BODY
CATTLE
DOMESTIC ANIMALS
FEMALE GENITALS
HORMONES
KETONES
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE PROTEINS
MOLYBDENUM COMPOUNDS
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
PREGNANES
PROTEINS
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
RUMINANTS
STEROID HORMONES
STEROIDS
TRANSITION ELEMENT COMPOUNDS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques