mRNA Translation in Xenopus Oocytes

The large size, resilience, and high translational capacity of the fullgrown Xenopus oocyte has made it a widely used system for the translation of microinjected natural and synthetic mRNAs. The injected and endogenous mRNAs compete for the oocyte translational machinery in a process that normally results in the translation of at least a fraction of the injected mRNA and in a concomitant decrease in the synthesis of endogenous proteins (1 ). The injected oocytes can survive in vitro for long periods in simple salt media, and a single oocyte can synthesize nanogram amounts of foreign protein/hour, This often allows the analysis to be performed on the material obtained from one or few oocytes. Additionally, the heterologous polypeptides can be subjected to various and posttranslational processing steps (including glycosylation, subunit assembly, movement along the secretory pathway, proteolytic processing, phosphorylation, acetylation, hydroxylation, amidation) many of which do not occur in the standard cell-free translation systems. Because of these and other characteristics, Xenopus oocytes have been successfully used in situations when more than the mere translation of the mRNA was required.