Transcription factor that binds a palindromic (canonical) core consensus DNA sequence 5'-CANNTG- 3' known as an E-box element, possibly as a heterodimer with other bHLH proteins (PubMed:24236640). Regulates endothelial cell proliferation, migration and tube-like structures formation (PubMed:24463812). Modulates endothelial cell differentiation through NOS3 (PubMed:24463812). May be implicated in specification and differentiation of neuronal cell lineages in the brain (By similarity). May participate in kidney development and may be involved in podocyte differentiation (By similarity). During early embryonic development is involved in tissue-specific differentiation processes that are dependent on class II bHLH factors and namely modulates the differentiation program initiated by the pro-endocrine factor NEUROG3 (By similarity). During myogenesis, may play a role during the transition of myoblasts from the proliferative phase to the differentiation phase (By similarity). Positively regulates HAMP transcription in two ways, firstly by acting directly on the HAMP promoter via E-boxes binding and indirectly through increased phosphorylation of SMAD protein complex (PubMed:24236640). Repress NEUROG3-dependent gene activation in a gene-specific manner through at least two mechanisms; requires only either the sequestering of a general partner such as TCF3 through heterodimerization, either also requires binding of the bHLH domain to DNA via a basic motif (By similarity). Efficient DNA binding requires dimerization with another bHLH protein. Interacts with NEUROG3 AND NEUROD1. Interacts with ZFPM2; mediates indirect interaction with GATA4. Forms a heterodimer with TCF3; repress transcription of TCF3 and TCF3/NEUROG3 dimer-induced transactivation of E box-dependent promoters. Expressed in lung, liver, kidney, heart and pancreas. Expressed in endothel of umbilical vessels. The bHLH domain mediates transcriptional repression by inhibiting TCF3 transcriptional activity through heterodimerization. Contains a degenerate basic motif not likely to bind DNA.