Raman Spectroscopic Markers for the Xenopus Laevis Oocyte Expression System

Studying membrane protein function using Xenopus laevis oocytes has been proven to be a successful toolsince its introduction more than three decades ago. Due to their great availability, large size and ease of handling, X. laevisoocytes are often superior when compared to other expression systems such as Escherichia coli or eukaryote expressionsystems. The Xenopus laevis oocyte expression system is able to efficiently transcribe and translate injected geneticinformation and to assemble, process, and target protein products. Protein characterization studies in intact whole cellinjected oocytes are done using established techniques such as electrophysiology, transport assays, and calcium imaging.Recently Xenopus oocytes have been analyzed using in-vivo NMR spectroscopy, and we wondered if it would be possibleto use Raman spectroscopy for non-invasive analysis of single oocytes. We present here evidence that it is possible toidentify Raman bands arising from heterologous expressed membrane proteins in stage VI oocytes. This opens thepossibility for integrating the Raman analysis with already established protein expression methods in order to yieldcomplementary information about membrane protein structure and function.