3] Expression of phototransduction proteins in Xenopus oocytes

Abstract

Xenopus oocytes provide a unique system for the expression of phototransduction Proteins. These large cells can be microinjected with RNA or DNA, and express a wide variety of proteins in a functional state. They are amenable to micropipette impalement for electrophysiological recording and intracellular injections. The oocyte G protein is able to interact with a wide variety of receptors, and thus has made the oocyte a convenient system for expression of seven transmembrane receptors. It is possible to inject either RNA derived from a cloned cDNA or cellular RNA, containing a complex mixture of proteins, some involved in signal transduction and biosynthesis. Thus, proteins that require a specific protein for proper folding or signaling can be identified or coexpressed. The methods presented in this chapter utilized this system to express both vertebrate and invertebrate light-sensitive pigments. In addition, the expression of a transducin subunit is characterized and the membrane association of the protein is illustrated.