24] Expression of gap junctional proteins in Xenopus oocyte pairs

Abstract

Publisher Summary This chapter provides describes gap junctional channels, which pose a unique problem not encountered with other ionic channels in that the formation of functional gap junctional channels requires the close apposition of two cell membranes. The main advantage of this system is that it provides a rapid method for assessing the function of normal and altered junctional proteins. However, a disadvantage is that it does not allow the study of single gap junctional channels. Injection of connexin 43 mRNA induces the formation of gap junctional channels. The junctional conductance in the mRNA-injected cell pairs is approximately two orders of magnitude larger than that observed in noninjected or water-injected controls. Expression of gap junctional proteins in Xenopus oocyte pairs allows the direct measurement of cell-to-cell coupling. This technique can be used to confirm that a cloned gene encodes a gap junction protein and to study the electrophysiological properties of the different connexin subtypes. It can also be a valuable tool in studying the relationship between structure and function.