Estradiol regulation of the synthesis of uterine proteins with clusters of proline- and glycine-rich peptide sequences.

Estradiol (E2) regulates the synthesis of uterine proteins at both the transcriptional and translational levels. E2 induces an increase in the specific amino acid acceptor activity of uterine tRNA, with the largest increases seen for proline, glycine and methionine. The synthesis of three uterine proteins that are rich in proline and glycine, estrogen receptor, progesterone receptor and glucose-6-phosphate dehydrogenase, is induced by E2. E2-induced increases in these proteins were preceded by an correlated with stimulation of tRNA acceptor activity for proline and glycine and these responses were specifically and simultaneously inhibited by prior azaserine treatment, which inhibits the E2-induced repair and synthesis of the 3'-CCA acceptor terminus of tRNAs. The high frequency and clustering of proline and glycine residues in estrogen receptor, progesterone receptor and glucose-6-phosphate dehydrogenase suggests that the translating ribosomes may slow down during synthesis of these proteins due to limiting levels of these tRNAs in E2-deprived uteri.