RING1 and YY1-binding protein (RYBP)

RING1 and YY1-binding protein (RYBP) is a multifunctional nuclear protein that acts as a component and regulator of the Polycomb repressive complex 1 (PRC1). RYBP interacts directly with RING1A, RING1B, and transcription factor YY1, as well as the PcG protein M33, serving both as a structural element and an enzymatic stimulator within PRC1 complexes. It contains an N-terminal C2C2 zinc finger motif and is highly conserved with YAF2, another Polycomb group protein and YY1 interactor. RYBP's inclusion in PRC1 complexes increases the E3 ligase activity for histone H2A lysine 119 monoubiquitination (H2AK119ub1), thereby enhancing gene repression and contributing to the maintenance of chromatin structure. Loss or dysregulation of RYBP alters histone modification patterns and gene expression, resulting in chromatin domain erosion and has been implicated in cancer and potentially other developmental or neurodevelopmental disorders. RYBP also has known roles in apoptosis through interactions with death effector domain proteins and apoptin. It is not a direct receptor, enzyme, transporter, or ion channel, but rather a chromatin-associated regulatory protein that may serve as a therapeutic target in contexts where PRC1 function is aberrant. No approved drugs specifically target RYBP; rather, drug development efforts in chromatin biology and Polycomb complexes may indirectly affect its activity.

Other names

DEDAFYEAF1APAP-1AAP1Apoptin-associating protein 1Death effector domain-associated factorYY1 and E4TF1-associated factor 1ring1 interactor RYBP

Modulation of Polycomb repressive complex 1 (PRC1) function; Stimulation of histone H2A ubiquitination (H2AK119ub1) via PRC1