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. 2021 Mar 18;22(6):3103. doi: 10.3390/ijms22063103

Figure 5.

Figure 5

Proposed molecular mechanisms of MYB transcription factor in the regulation of expression of target genes [148]. (A) Anthocyanin synthesis is initiated in binding directly to target gene by the MYB activator. (B) The MYB activator, WD40 repeat (WDR), and bHLH1 proteins form an MBW activation complex that activated structural genes and promoted the accumulation of anthocyanin. (C) The MYB activator, WDR, and bHLH1 proteins form an MBW activation complex that activated the expression of bHLH2 and structural genes and promote the accumulation of anthocyanin. (D) MYB repressors are activated by the MBW complex, that binding to the promoter of the terminal structural gene in the anthocyanin biosynthesis pathway. (E) MYB repressors could inhibit anthocyanin biosynthesis by incorporating into the MBW activation complex as a corepressor or by binding to the promoter of target genes directly. (F) Feedback inhibition is provided by R3-MYB repressors; these are activated by the MBW complex and inhibit the formation of new MBW complexes by titrating bHLH factors.