Hormonal influences on the middle-affinity estrogen-binding sites in the liver of the newt Pleurodeles waltl

Nuclear estrogen binding sites in the liver of the newt Pleurodeles waltl

Previous investigations of the liver estrogen-specific binding in the newt, Pleurodeles waltl, have identified in the cytosol fraction, only from normal males, a new middle-affinity estrogen-binding component (MEBC) displaying the properties of type II sites reported in various tissues of vertebrates. The present work demonstrates that MEBC sites are not unique to the male but are also present in the nuclei of female animals. However, comparative study between males and females of liver nuclear sites under various extraction conditions shows sex-linked differences in the subnuclear localization. The relationships between the association states of MEBC in the nuclear compartment according to sex and their presence or absence in the cytosol fraction are discussed.