High-Throughput Protein Expression Screening of Cell-Surface Protein Ectodomains.

Cell-surface receptors can be difficult to express and purify for structural and biochemical studies due to low expression levels, misfolding, aggregation, and instability. Cell-surface receptor ectodomains are more amenable to large-scale production, but this requires designing and testing various truncation constructs. However, since each protein is unique, testing these constructs individually for many targets is a time-consuming process. In this context, we present a high-throughput ELISA fluorescence approach that allows the rapid assessment of numerous recombinant constructs simultaneously. Cell-surface ectodomains are expressed in small scale, enzymatically biotinylated, and detected using a C-terminal His-tag. As an example, we tested the expression of truncation constructs for the neurexin, neuroligin, and latrophilin families and show that the small-scale ELISA allowed us to prioritize well-expressing construct for large-scale production. By employing this method, one can efficiently detect clones with low expression levels, streamlining the process and saving valuable time in identifying optimal candidates for further study.