Electrical recordings from cloned sodium channels expressed in Xenopus Oocytes.

Oocytes from Xenopus laevis provide an efficient translation system for expressing ionic channels under in vivo equivalent conditions. This transcription of genetic information starts by the microinjection of mRNA that has been either extracted directly from cells or derived from cDNA. The elucidation of the cDNA encoding for ionic channels—such as acetylcholine receptors and sodium channels from different origins—has led to investigations of the structure–function relationship of these channels. This is done by either assembling multisubunit channels with elements from various species or by introducing artificial mutations. This approach has been used to assign specific functions to individual subunits of the nicotinic acetylcholine receptor and to analyze functional properties of acetylcholine receptor mutants altered by site-directed mutagenesis, enabling localization of functional regions within a subunit