Transcription factor that binds DNA in a non-specific manner, yet also specifically recognizes the core sequence 5'-CAC[GA]TG-3'. Activates the transcription of growth-related genes. Efficient DNA binding requires dimerization with another bHLH protein. Binds DNA as a heterodimer with max (By similarity). High levels are seen in the kidney, gills and uterus. Found in low abundance in the two-cell through early somite stages (<1.5 through 12 hours) and increases during later stages of growth and organ development. The 9aaTAD motif is a transactivation domain present in a large number of yeast and animal transcription factors.