An estrogen-dependent polysomal protein binds to the 5′ untranslated region of the chicken vitellogenin mRNA

An estrogen-dependent protein present in chicken liver polysomes binds to the 5' untranslated region of the chicken vitellogenin II mRNA. Competition binding assays with different RNAs indicate that the binding of the polysomal protein to this region is sequence specific. Of the tissues tested, this RNA binding activity is liver specific. In vivo kinetics of appearance of the binding activity following a single injection of estrogen to immature chicks are similar to the rate of accumulation of vitellogenin mRNA. The molecular weight of the polysomal protein has been estimated to be 66,000 on the basis of UV crosslinking and subsequent SDS polyacrylamide gel electrophoresis. In vitro RNA decay assays carried out with a minivitellogenin mRNA suggest that the estrogen-dependent polysomal protein may be involved in the estrogen-mediated stabilization of the chicken vitellogenin II mRNA.