Fig. 6. The CCT domain of CO is necessary for the in vitro interaction with SPA1. (A) Schematic representation of the deletion-derivatives of CO or His₆-CO used in the in vitro binding assay. (B) Mapping of the SPA1-interacting domain of CO. Recombinant ³⁵S-labelled CO or indicated CO-deletion proteins were incubated with partially ³⁵S-labelled GAD-SPA1 or GAD, respectively, and co-immunoprecipitated with anti-GAD antibodies. Supernatant fractions (1.6%) and 33.3% of the pellet fractions were resolved by SDS-PAGE and visualized by autoradiography using a phosphorimager. (C) Quantification of the fractions of prey proteins that were co-immunoprecipitated by the indicated bait proteins GAD-SPA1 or GAD. Error bars depict the s.e.m. from two replicate experiments.