Transcription factor. Probably binds E-box motifs 5'-CANNTG- 3' in complex with transcription factor TCF3/E12. Negatively modulates transcription of target genes such as CDH1/E-cadherin, perhaps by recruiting the PRC2 repressive complex to regulatory elements. Regulates ameloblast development and tooth germ growth, perhaps acting by positively modulating migration of inner enamel epithelium (IEE) cells. Plays a role in enamel formation. . This is the function of ASCL5 (achaete-scute family bHLH transcription factor 5, Ensembl gene identifier ENSG00000232237).