Function
Inhibits E-box-mediated binding and transactivation of bHLH factors. Inhibitory effect is similar to that of ID proteins. Inhibits the formation of TCF3 and MYOD1 homodimers and heterodimers. Lacks DNA binding activity. May be involved in the regulation or modulation of smooth muscle contraction of the uterus during pregnancy and particularly around the time of delivery. Seems to play a role in the inhibition of myogenesis.