Xenopus Oocyte Microinjection and Ion-Channel Expression

It is now over 20 years since the seminal studies by John Gurdon and colleagues established that Xenopus laevis oocytes, when injected with messenger RNA (mRNA), were able after a period of incubation to translate the mRNA and appropriately synthesize the relevant protein (Gurdon et al., 1971; Gurdon 1974). In this study, rabbit reticulocyte 9S mRNA was injected and the oocytes produced globins. This important observation led to an amazing variety of proteins being expressed in Xenopus oocytes following injection with mRNAs extracted from different sources, including, for example, viral (adenovirus, mouse mammary tumor virus) and plant mRNAs (barley and maize), and also invertebrate (locust muscle, honey bee), and vertebrate tissue mRNAs (cat skeletal muscle, mouse kidney, rat spleen, Torpedo electric organ; see Lane, 1983; Colman, 1984; Soreq, 1985 for reviews). The value of the Xenopus oocyte for in vitro translation studies is now recognized by the oocyte’s ability to correctly assemble proteins composed of individual subunits and also to ensure the appropriate posttranslational processing of the protein, i.e., insertion into the cell membrane or secretion of the protein product (Lane, 1983; Soreq, 1985).