Extended Data Fig. 1. Quality control of proteins used in this study.

a. Representative Coomassie blue-stained SDS PAGE gels showing the supernatant from the EPD assays used for quantification. b-c. Size exclusion chromatograms through a Superdex 200 Increase column (b) and Coomassie blue-stained SDS PAGE gels (c) showing loading control of indicated Retriever constructs used in pull-down assays shown in Fig. 2f. d. Coomassie blue-stained SDS PAGE gel showing MBP pull-down of indicated Retriever constructs using MBP-tag as a negative control, in comparison to MBP-CCDC22-CCDC93 VBD pull-down in Fig. 2g.