Estrogen action in rooster liver. Modification of a tRNASer-inactivating activity

The hepatic synthesis of the yolk protein, phosvitin, can be induced in rooster by the administration of estrogen and this provides a model for studying the regulatory mechanisms involved. Since phosvitin is unusually rich in serine the effect of estrogen on the metabolism of serine transfer RNA (tRNASer) was examined. Rooster liver contains an activity capable of inactivating rooster liver tRNASer. This activity has specificity in that it inactivates only part of the tRNASer in the unaminoacylated form. Upon estrogen administration this activity is modified with a change in specificity and the modified activity is able to inactivate only a significantly smaller amount of tRNASer than the unmodified activity. This novel mechanism may be involved in the regulation of some species of tRNASer and thus may be part of the translational control involved in estrogen-induced phosvitin synthesis.