Membrane protein expression in cell-free systems.

Cell-free expression has emerged as a promising tool for the fast and efficient production of membrane proteins. The rapidly growing number of successfully produced targets in combination with the continuous development of new applications significantly promotes the distribution of this technology. Membrane protein synthesis by cell-free expression does not appear to be restricted by origin, size or topology of the target, and its global application is therefore a highly valuable characteristic. The technology is relatively fast to establish in standard biochemical labs, and it does not require expensive equipment. Moreover, it enables the production of membrane proteins in completely new modes, like the direct translation into detergent micelles, which is not possible with any other expression system. In this protocol, we focus on the currently most efficient cell-free expression system for membrane proteins based on Escherichia coli extracts.