Fig. 1. The WD40 domain of COP1 is required for interaction with STO, STH and HY5. (A) Diagrams of wild-type COP1 and three mutated versions. The total number of amino acids in each protein are indicated on the right. (B) Summary of the detected interactions between the four versions of COP1 and the three interactive partners. The STO and STH experiments were performed with Gal4-BD-fused COP1 proteins and the HY5 experiments were performed with AD-fused COP1 proteins. ‘Yes’ represents >50-fold activation over background for HY5 and 5- to 15-fold activation over background for STO and STH; ‘no’ represents background activation. See text for additional detail.