Flow diagram of our fluorescent cassette-based strategy to construct the AB fusion cassette. First, the fluorescent cassettes A and B are created by insertion of the respective domains into the pCfvtx vector. Then, cassette A and B is created by the excision of Venus by PmeI restriction and then self-ligation. The path of the thick arrows highlight the fusion steps required for creating the AB fusion cassette. The fluorescent cassette B is ligated to cassette A to create a fluorescent cassette AB. The final AB fusion cassette is created by the excision of Venus as described previously.