[Multicomponent system of estrogen-binding proteins of liver cytosol: species differences in rats, mice and guinea pigs].

Estradiol (E2) binding proteins from the liver cytoso-of mature male and female rats, mice, guinea pigs, and rabbits were investigated by gel filtration on Sepharose 6B columns. Components with Stokes radii (a) 6--7 and 2.5 nm which form specific stable complexes with E2 were found in female rats and female and male mice. The liver of male rats and male and female guinea pigs contain specific E2-binding proteins with a-about 6--7, 2.5 and less than 2.0 nm. E2 complexes with components having a values 6--7 and less than 2.0 nm relatively stable, whereas E2 complex with a component possessing a value about 2.5 nm is capable of dissociating completely within 45 minutes. It is suggested that at least some of the components of the discovered heterogenic populations of E2-binding proteins could participate in the estrogen signal reception by the liver.