PRC1

PRC1 is an acronym that may refer to two distinct protein complexes in biology. The Protein Regulator of Cytokinesis 1 is a conserved microtubule-associated protein required for proper cytokinesis. During mitosis, PRC1 localizes to the spindle midzone, crosslinking antiparallel microtubules and forming the central spindle, a scaffold for cleavage furrow ingression. It functions in cooperation with the centralspindlin complex and with mitotic kinases such as CDK1 and PLK1 to control the timing of spindle midzone assembly. PRC1 is a dimer that uses a central coiled-coil region for self-association and a microtubule-binding domain; its activity is regulated by phosphorylation, ensuring localization to the spindle during anaphase. Loss of PRC1 leads to defects in cytokinesis and may cause binucleation and aneuploidy. PRC1 has orthologs in many eukaryotes and is essential for cell division in higher eukaryotes.

Polycomb Repressive Complex 1 is a chromatin-modifying E3 ubiquitin ligase that contributes to transcriptional repression of developmental genes. It catalyzes monoubiquitination of histone H2A at lysine 119 (H2AK119ub1). Canonical PRC1 and noncanonical PRC1 differ in subunit composition and recruitment mechanisms. Core activity is provided by a RING1A or RING1B subunit in partnership with a BMI1-family protein, while additional components such as CBX proteins and PHC family members help mediate chromatin compaction and targeting. PRC1 activity often works in concert with PRC2, which deposits H3K27me3 marks that recruit additional PRC1 complexes. PRC1 plays a central role in development, X-chromosome inactivation, imprinting, and stem-cell biology, and its dysregulation is linked to cancer and developmental disorders.