Integral membrane proteins (IMPs) play diverse roles in cells ranging from transport to signal transduction. Simple, reliable over-expression systems for the production of recombinant IMPs will relieve a serious bottleneck in structural biology efforts towards characterization of IMPs. To this end we have developed novel flow cytometric assays to quantitatively assess the amount of properly-folded recombinant IMP present in the membrane of the bacterium E. coli. Several model E. coli IMPs as well as a mammalian G-protein coupled receptor (GPCR) are currently being studied using these flow cytometric assays. The effects of systematic depletion or over-expression of components of the signal recognition particle (SRP) pathway as well as several proteins implicated in membrane protein quality control on the expression of the model IMPs was investigated. We are also currently using the flow cytometric assay to screen a genomic library for novel effectors of membrane protein biogenesis.