The Notch signaling pathway controls various cellular interactions that are important for the specification of a variety of fates in both vertebrates and invertebrates. Key players in the Notch pathway are the TLE genes (for transducin-like enhancer of split, also designated ESG for enhancer of split groucho), which are human homologs of the Drosophila groucho gene. TLE6 (transducin-like enhancer of split 6), also known as GRG6, is a 449 amino acid cytoplasmic protein belonging to the WD repeat groucho/TLE family. As a member of the subcortical maternal complex (SCMC), TLE6 is essential for zygotes to progress beyond the first embryonic cell divisions. TLE6 contains seven WD repeats, a motif known to mediate protein-protein interactions. The WD40 repeat family of proteins is suggested to be involved in signal transduction, RNA processing, gene regulation, vesicular trafficking, cytoskeletal assembly and may play a role in the control of cytotypic differentiation.