Post-translational control of ribosomal protein L1 accumulation in Xenopus oocytes.

A functional ribosomal protein mRNA, encoding the 60 S subunit protein L1, has been synthesized in vitro using bacteriophage SP6 RNA polymerase. This mRNA directs the synthesis of a product indistinguishable from L1 protein purified from Xenopus ovarian ribosomes. Our results show that L1 synthesis in stage VI oocytes increases in response to microinjection of exogenous SP6-L1 mRNA, but excess L1 protein is not stably accumulated. These results indicate that dosage compensation does not occur at the translational level for this ribosomal protein mRNA and that the abundance of this protein in fully grown oocytes is subject to post-translational regulation.