Co-expression of protein complexes in prokaryotic and eukaryotic hosts: experimental procedures, database tracking and case studies

Structure determination and functional characterization of macromolecular complexes requires the purification of the different subunits in large quantities and their assembly into a functional entity. Although isolation and structure determination of endogenous complexes has been reported, much progress has to be made to make this technology easily accessible. Co- expression of subunits within hosts such as Escherichia coli and insect cells has become more and more amenable, even at the level of high- throughput projects. As part of SPINE ( Structural Proteomics In Europe), several laboratories have investigated the use co- expression techniques for their projects, trying to extend from the common binary expression to the more complicated multi- expression systems. A new system for multi- expression in E. coli and a database system dedicated to handle co- expression data are described. Results are also reported from various case studies investigating different methods for performing co- expression in E. coli and insect cells.