Figure 1. A. Protein-protein interaction between bHLH transcription factors and JAZ proteins. A summary of yeast two-hybrid results to assay for interactions between bHLH transcription factors as bait (BD) and JAZ repressors as prey (AD) (A), and the opposite combination (JAZ proteins as bait and bHLH proteins as prey) (B). AD, DNA activation domain; BD, DNA binding domain. Based on the number of colonies formed, the strength of each interaction was rated as strong (+++), medium (++), weak (+), or undetectable (–). (C), (D) Quantitative assays of β-galactosidase activity using o-nitrophenyl-β-d-galactopyranose as a substrate to determine protein interactions between JAM1 and JAZ proteins. Results are shown as the mean ± SD for biologically independent experiments (n = 3). (E) The interaction of truncated JAM1 derivatives with full-length JAZ3 was tested. (F) Alignment of the amino acid sequences of JAM1, JAM2, JAM3, MYC2, MYC3, and MYC4. Identical and similar amino acids are shaded black and gray, respectively. Red boxes indicate the nuclear localization signals. Orange lines under the sequences indicate the JAZ interaction domain of MYC2 and MYC3.¹⁸ Light blue lines above the sequences indicate the conserved amino acid residues within a JAZ-interacting domain among JAM1, JAM2, MYC2, MYC3, and MYC4, but not JAM3. Figure 1B. Protein-protein interaction between bHLH transcription factors and JAZ proteins. A summary of yeast two-hybrid results to assay for interactions between bHLH transcription factors as bait (BD) and JAZ repressors as prey (AD) (E) The interaction of truncated JAM1 derivatives with full-length JAZ3 was tested. (F) Alignment of the amino acid sequences of JAM1, JAM2, JAM3, MYC2, MYC3, and MYC4. Identical and similar amino acids are shaded black and gray, respectively. Red boxes indicate the nuclear localization signals. Orange lines under the sequences indicate the JAZ interaction domain of MYC2 and MYC3.¹⁸ Light blue lines above the sequences indicate the conserved amino acid residues within a JAZ-interacting domain among JAM1, JAM2, MYC2, MYC3, and MYC4, but not JAM3.