Dimerization through the helix-loop-helix motif enhances phosphorylation of the transcription activation domains of myogenin.

摘要: The muscle-specific basic helix-loop-helix (bHLH) protein myogenin activates muscle transcription by binding to target sequences in promoters and enhancers as a heterodimer with ubiquitous bHLH proteins, such the E2A gene products E12 E47. We show that dimerization potentiates phosphorylation of at sites within its amino- carboxyl-terminal activation domains. Phosphorylation these was mediated region dependent on but not DNA binding. Mutations dimerization-dependent resulted enhanced transcriptional activity myogenin, suggesting their diminishes myogenin's activity. ability potentiate suggests induces conformational change unmasks otherwise cryptic or proteins recruit kinase for which is substrate. That diminished are targets interferes expression.