PYGO2 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, as well as a histone methylation reader that binds di-and trimethylated lysine 4 of histone H3 (H3K4me2/3). Moreover, PYGO2 acts as a chromatin remodeler in a testis-specific and Wnt-unrelated manner. It also mediates chromatin regulation and links Wnt signaling and Notch signaling to suppress the luminal/alveolar differentiation competence of mammary stem and basal cells. Furthermore, PYGO2 plays a new role in rRNA transcription during cancer cell growth. It regulates mammary tumor initiation and heterogeneity in MMTV-Wnt1 mice. PYGO2 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.",