Hairy/enhancer-of-split related with YRPW motif protein 1 (Hey1)

Transcriptional repressor which binds preferentially to the canonical E box sequence 5'-CACGTG-3'. Downstream effector of Notch signaling required for cardiovascular development.

Especially required for its Notch-induced endocardial epithelial to mesenchymal transition, which is itself criticial for cardiac valve and septum development. May be required in combination with HEY2 to specify arterial cell fate or individuality.