Characterization and partial purification of a male specific hepatic estrogen binding protein
In order to characterize the estrogen binding protein (MEB) binding site and its interaction with steroids, the effect of single substituent variations of estradiol on MEB affinity was tested. As assessed by relative binding affinities, MEB exhibits a unique specificity for steroidal estrogens. Free C(3) and C(17) hydroxyl groups are required for an effective binding interaction. Androgens do not bind as effectively as estrogens, whereas nonsteroidal estrogens such as DES, antiestrogens such as tamoxifen and 4-hydroxytamoxifen, progestins and glucocorticoids do not interact with the MEB estradiol binding site. Several physicochemical characteristics of MEB were determined. MEB has a molecular weight of 25-30 kDa. The kinetics of (/sup 3/H)E/sub 2/ association and dissociation at 4/sup 0/C are very rapid, with t/sub 1/2/ values of less than 5 seconds. These rapid binding kinetics are also observed for (/sup 3/H)E/sub 3/, (/sup 3/H)E/sub 1/, (/sup 3/H)5..cap alpha..-androstan-3..cap alpha.., 17..beta..-diol, and (/sup 3/H)2-OMeE/sub 3/. Divalent cations inhibit MEB estradiol binding, an effect reversed by EDTA. Other characteristics such as temperature and pH stability, and absence from the nuclear fraction of the hepatocyte further distinguish it from the estrogen receptor.
- Research Organization:
- Pittsburgh Univ., PA (USA)
- OSTI ID:
- 6292125
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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ESTROGENS
BIOCHEMICAL REACTION KINETICS
PROTEINS
CHEMICAL COMPOSITION
RECEPTORS
SPECIFICITY
AFFINITY
EDTA
FRACTIONATION
LIVER
MOLECULAR WEIGHT
TRACER TECHNIQUES
TRITIUM COMPOUNDS
AMINO ACIDS
BODY
CARBOXYLIC ACIDS
CHELATING AGENTS
DIGESTIVE SYSTEM
GLANDS
HORMONES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MEMBRANE PROTEINS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
REACTION KINETICS
SEPARATION PROCESSES
STEROID HORMONES
550201* - Biochemistry- Tracer Techniques