PLK3 Polo Box Domain Protein, Human (MBP, His)

The PLK3 Polo Box Domain is a serine/threonine-protein kinase involved in cell cycle regulation, stress response, and Golgi disassembly. It recognizes and phosphorylates substrates bearing specific phospho-motifs via its POLO box domains, with known targets including ATF2, BCL2L1, CDC25A, CDC25C, CHEK2, HIF1A, JUN, p53/TP53, p73/TP73, PTEN, TOP2A, and VRK1. Functionally, it regulates S-phase entry and cytokinesis (e.g., by phosphorylating BCL2L1 to control the G2 checkpoint and mitotic cytokinesis). Rapidly activated under stresses (e.g., ionizing radiation, ROS, hyperosmotic stress, UV, hypoxia), it coordinates DNA damage response via phosphorylating CDC25A, p53/TP53, and p73/TP73. Key examples include: ROS-induced p53/TP53 phosphorylation promoting apoptosis; DNA damage-triggered CHEK2 phosphorylation activating the G2/M checkpoint while suppressing p73/TP73's transcriptional and pro-apoptotic activities. It also phosphorylates HIF1A/JUN during hypoxia and ATF2 in hyperosmotic-stressed corneal epithelium. During mitosis, it drives MEK1/MAP2K1-dependent Golgi fragmentation through VRK1 phosphorylation. Potentially participates in endomitosis (a hallmark of megakaryocyte differentiation) via CIB1 interaction.