basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana protein FAMA and similar proteins
The family includes several bHLH transcription factors from Arabidopsis thaliana, such as FAMA, MUTE and SPEECHLESS, which work together to regulate the sequential cell fate specification during stomatal development and differentiation. FAMA, also termed AtbHLH97, or EN 14, is a transcription activator required to promote differentiation and morphogenesis of stomatal guard cells and to halt proliferative divisions in their immediate precursors. It mediates the formation of stomata. MUTE, also termed AtbHLH45, or EN 20, is required for the differentiation of stomatal guard cells, by promoting successive asymmetric cell divisions and the formation of guard mother cells. It promotes the conversion of the leaf epidermis into stomata. SPEECHLESS, also termed AtbHLH98, or EN 19, is required for the initiation and the formation of stomata, by promoting the first asymmetric cell divisions. FAMA, MUTE and SPEECHLESS form heterodimers with SCREAM/ICE1 and SCRM2 to regulate transcription of genes during stomatal development.
Jiyao W et al.(2023). "The conserved domain database in 2023.",