Vitellogenin, the precursor of egg yolk phosphoproteins, is synthesized in the liver of the laying hen but is not normally synthesized by roosters. Administration of 17β-estradiol to roosters induces the synthesis of large amounts of this protein and its messenger RNA. We have purified vitellogenin messenger RNA from the livers of estrogen-treated roosters and have characterized it as follows: it is capable of directing the synthesis of the full sized vitellogenin polypeptide [M(r)=240,000] in a cell-free translation system derived from wheat germ; its molecular weight, determined by both agarose gel electrophoresis under fully denaturing conditions and by electron microscopy, is 2.3 to 2.35 x 106, which is approximately 10% (600 nucleotides) longer than is required to encode the vitellogenin polypeptide; and complementary DNA synthesized from the purified messenger RNA hybridizes to its template with the kinetics expected for a single species the size of vitellogenin messenger RNA. We have used vitellogenin complementary DNA to quantitate vitellogenin messenger RNA in the livers of normal and estrogen-treated roosters, and have found that following primary treatment of the rooster with estrogen the level of this messenger RNA rises from 0-5 molecule(s) per cell to approximately 5000 molecules per cell. The results reported here support a model in which primary hormonal induction of vitellogenin synthesis involves activation of a dormant gene in a fully differentiated and metabolically active cell.
|Number of pages||10|
|Journal||Journal of Biological Chemistry|
|State||Published - 1977|