Size-exclusion chromatography docking assay. Data for Venus+CDDBaeM are shown here (data for all Venus+CDD constructs are reported in Figures S2 and S3). (A) Individually, the cognate constructs Venus+CDDBaeM and NDDBaeN+mTurquoise2 elute at 17 mL. A coinjection results in a species that elutes at 15 mL. (B) A coinjection of the noncognate constructs Venus+CDDBaeM and NDDMlnC+mTurquoise2 does not generate an earlier-eluting species. (C) Venus+CDDBaeM paired with each of the NDD+mTurquoise2 constructs shows that only the coinjection with NDDBaeN+mTurquoise2 results in complex formation (NDDBaeN+mTurquoise2, red; NDDDifG+mTurquoise2, orange; NDDMlnC+mTurquoise2, green; NDDMlnD+mTurquoise2, light blue; NDDMlnE+mTurquoise2, navy; NDDMlnG+mTurquoise2, purple). Coomassie-stained SDS-PAGE gels confirm that both the Venus+CDDBaeM and NDDBaeN+mTurquoise2 constructs are present in the early eluting species (boxed in green). Legend for all SDS-PAGE gels: Lane 1, ladder (PageRuler Prestained Protein, Thermo Scientific); lanes 2–13, fractions 12–23; lane 14, Venus+CDD construct; lane 15, NDD+mTurquoise2 construct. Matched NDDBaeN+mTurquoise2 and Venus+CDDBaeM appear in lanes 3–5 (corresponding to fractions 13–15), while mismatched constructs do not.