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6303881 
Journal Article 
Rat estradiol binding plasma protein (EBP) 
Raynaud, JP; Mercier-Bodard, C; Baulieu, EE 
1971 
1 
Steroids
ISSN: 0039-128X
EISSN: 1878-5867 
18 
6 
767-788 
English 
5135733 
WOS:A1971L371700007 
The interaction of estradiol and testosterone with rat plasma proteins has been studied by equilibrium dialysis, sucrose gradient centrifugation, column chromatography and polyacrylamide gel electrophoresis. Binding results were calculated according to the proportion graph methodology.

These methods have enabled the detection of high concentrations (80 μM) of a specific Estradiol Binding Plasma Protein (EBP) of a sedimentation coefficient of approximately 4.5 S in the plasma of 20-day old fetuses of both sexes. A decrease in this concentration has been noted during the first four weeks after birth, the level falling to zero in normal and castrated adults. EBP is also found in pregnancy plasma.

This protein binds estradiol with an intrinsic association constant of about 108M−1 at 4°C. Estrone, unlike several synthetic estrogens, is bound with greater affinity, whereas non estrogenic steroids including testosterone are not bound at all.

EBP is separated from rat serum albumin by polyacrylamide gel electrophoresis.