Ways & Means Optimization of Protein Production in Mammalian Cells with a Coexpressed Fluorescent Marker

Summary ity to fold or be targeted properly in the bacterial cell.Such problems inevitably result in low levels of expres- The expression of mammalian proteins in sufficient sion or protein misfolding (Baneyx, 1999; Makrides, abundanceandqualityforstructuralstudiesoftenpre-sents formidable challenges. Many express poorly in 1999; Geisse et al., 1996). Thus, despite drawbacks in bacterial systems, whereas it can be time consuming efficiency, alternative expression systems based on and expensive to produce them from cells of higher eukaryotic hosts have been developed for large-scale organisms. Here we describe a procedure for the di- protein production. These include expression in yeast, rect selection of stable mammalian cell lines that ex- insectcells,andmammaliancells,allofwhichhavebeen press proteins of interest in high yield. Coexpression used successfully in producing proteins for structure ofamarkerprotein,suchasgreenfluorescentprotein, determination. islinked tothatof thedesiredproteinthrough aninter-