Fig. 1. Deriving a second-generation CDP library with improved surface folding characteristics.
(A) Illustration of mammalian surface display principle. If the CDP is not tagged (vector SDGF), tagged (e.g., biotin) target along with a fluorescent co-stain (e.g., streptavidin) stains cells to enrich for target-binding CDPs of interest. When the CDP itself is tagged (e.g., 6xHis, vector SDPR), the fluorescent co-stain (e.g., anti-6xHis) will detect intact CDPs on the surface of the cell. (B and C) High surface folding scores (B) from pooled analysis of library NCL1 permitted homology-based selection from a large CDP library (C) to create a second-generation CDP library, NCL2. (D) Flow-based comparison of SDPR-cloned 6xHis-tagged NCL1 and NCL2 with or without trypsin (5 or 20 μg/mL, 5 mins) followed by DTT treatment (5 mins) and subsequent anti-6xHis antibody staining.