Attachment of vitellogenin genes to the nucleoskeleton accompanies their activation.

We have investigated the association of an inducible RNA polymerase II gene with the nucleoskeleton using the estrogen-inducible expression of the B2 vitellogenin gene in Xenopus liver as a model system. Using only physiological extraction conditions we find that the promoter region of the gene is strongly associated with the nucleoskeleton when it is transcriptionally active but much less so when it is inactive. We also find that the estrogen receptor protein, which is responsible for activation of this gene, is itself found associated with the nucleoskeleton. Finally, we show that newly synthesized, unspliced vitellogenin mRNA is also found on the nucleoskeleton. Our data suggest that expression of the B2 vitellogenin gene occurs only after it has become attached to the nucleoskeleton.