PYGO1 is a homolog of Drosophila melanogaster protein pygopus (dPYGO), which is a fundamental Wnt signaling transcriptional component in Drosophila. It functions as a context-dependent beta-catenin coactivator, and binds di- and trimethylated lysine 4 of histone H3 (H3K4me2/3). PYGO1 is essential for the association with Legless (Lgs)/Bcl9 that acts as an adaptor between Pygopus (Pygo) and Arm/beta-catenin. PYGO1 contains a plant homeodomain (PHD) finger, which is important for Lgs/Bcl9 recognition as well as for the regulation of the Wnt/beta-catenin signaling pathway.
Jiyao W et al.(2023). "The conserved domain database in 2023.",