PRC1 is a microtubule binding and bundling protein essential to maintain the mitotic spindle midzone []. It is a key regulator of cytokinesis that cross-links antiparallel microtubules at an average distance of 35 nM [, ]. PRC1 is also required for KIF14 (a kinesin-3 family motor protein) localisation to the central spindle and midbody [, , ]and is required to recruit PLK1 to the spindle. It stimulates PLK1 phosphorylation of RACGAP1/HsCyk-4 to allow recruitment of ECT2 to the central spindle [].
SCML2 is a mammalian Polycomb-group protein, which associates with the Polycomb repressive complex-1 (PRC1) that is essential for the epigenetic regulation of gene expression. Isoform SCML2A has been shown to bind to PRC1 via its SPM domain and to interact with ncRNAs through a novel RNA-binding region (RBR). The RBR is necessary for targeting of SCML2A to chromatin and PRC1 recruitment, suggesting a role for ncRNAs in regulating SCML2 function [].This entry represents the RNA-binding region of SCML2, also found in other Polycomb-group proteins.
E3 ubiquitin-protein ligase RING2 () mediates monoubiquitination of 'Lys-119' of histone H2A (H2AK119Ub) [], which is a specific tag for epigenetic transcriptional repression and participates in X chromosome inactivation of female mammals []. RING2 is a component of the PRC1 complex [], and other chromatin-associated Polycomb (PcG) complexes such as BCOR []. It is also a component of the MLL1/MLL complex [].
Mammalian Polycomb-like gene MTF2/PCL2 forms a complex with Polycomb repressive complex-2 (PRC2) and collaborates with PRC1 to achieve repression of Hox gene expression []. The human MTF2 gene is expressed inthree splicing variants, each of them contains the short C-terminal domain defined here.
This is a family of microtubule associated proteins, including MAP65 (MAP65-1/2/3/4/5/6/7/8/9) from Arabidopsis, Ase1 from yeast, and PRC1 from mammals.Ase1 is required for spindle elongation and stabilisation. It is cell cycle-regulated by anaphase promoting complex []. It is a potential Cdc28p substrate []. MAP65-1 plays a role in stabilising anti-parallel microtubules in the central spindle at anaphase to early cytokinesis. MAP65-1 is cell cycle regulated by phosphorylation [, , , , ].PRC1 is a microtubule binding and bundling protein essential to maintain the mitotic spindle midzone []. It is a key regulator of cytokinesis that cross-links antiparallel microtubules at an average distance of 35 nM [, ]. PRC1 is also required for KIF14 (a kinesin-3 family motor protein) localisation to the central spindle and midbody [, , ]and is required to recruit PLK1 to the spindle. It stimulates PLK1 phosphorylation of RACGAP1/HsCyk-4 to allow recruitment of ECT2 to the central spindle [].
The RAWUL domain is found at the C terminus of poly-comb group RING finger proteins. It contains a variant ubiquitin-like fold with a distinct conserved surface region. The conserved surface found in this domain is responsible for interaction with Cbx members of the PRC1 (polycomb repression complex 1) and homodimer formation []. The RAWUL domain binds directly to PUFD, a domain on BCOR proteins (BCL6 corepressor). BCOR has emerged as an important player in development and health [].
Proteins included in this entry have an N-terminal RanBP2-type zinc finger and a Yaf2/RYBP C-terminal binding motif. Proteins with these regions include Yaf2 and RYBP proteins, which are homologous parts of the PRC1 complex [].RYBP is a zinc finger protein with an essential role during embryonic development, which binds transcriptional factors, Polycomb products, and mediators of apoptosisis []. RYBP also binds ubiquitin and Cbx proteins via the C-terminal docking module [, ]. RYBP is natively unstructured until it binds to the C-terminal region of the Polycomb protein Ring1B or to DNA []. Yaf2 binds to MYC and inhibits MYC-mediated transactivation [].
PcG proteins form large multiprotein complexes (PcG bodies) which are involved in the stable repression of genes involved in development, signaling or cancer via chromatin-based epigenetic modifications. Mammalian PRC1 includes canonical (cPRC1) and non-canonical complexes; cPRC1, contains four core subunits including one CBX protein (CBX2, CBX4, and CBX6-CBX8) that binds H3K27me3. CBX family members have different affinity for H3K27me3, with CBX7 having the highest binding capability [, ].This entry represents CBX7 []. In pluripotent cells, CBX7 is the main PRC1-associated Cbx protein and plays an important role in the maintenance of pluripotency [].
This motif is found in the C-terminal region of the Yaf2 and RYBP proteins, which are homologous parts of the PRC1 complex [].RYBP is a zinc finger protein with an essential role during embryonic development, which binds transcriptional factors, Polycomb products, and mediators of apoptosisis []. RYBP also binds ubiquitin and Cbx proteins via the C-terminal docking module [, ]. RYBP is natively unstructured until it binds to the C-terminal region of the Polycomb protein Ring1B or to DNA []. Yaf2 binds to MYC and inhibits MYC-mediated transactivation [].
E3 ubiquitin-protein ligase RING1 () is one of the three E3 ubiquitin-protein ligases that mediate monoubiquitination of 'Lys-119' of histone H2A, which is a specific tag for repression of epigenetic transcription and particularly for inactivation of chromosome X of female mammals [, ]. RING1 is a component of the Polycomb group (PcG) multiprotein PRC1-like complex, the repressive BCOR complex [], and the the E2F6.com-1 complex in G0 phase []. RING1 has a RING-type zinc finger.E3 ubiquitin-protein ligase RING2 () mediates monoubiquitination of 'Lys-119' of histone H2A (H2AK119Ub) [], which is a specific tag for epigenetic transcriptional repression and participates in X chromosome inactivation of female mammals []. RING2 is a component of the PRC1 complex [], and other chromatin-associated Polycomb (PcG) complexes such as BCOR []. It is also a component of the MLL1/MLL complex [].This entry includes E3 ubiquitin-protein ligase RING1/RING2.
RING1 is a transcriptional repressor associated with the Polycomb group (PcG) protein complex involved in stable repression of gene activity. It is a core component of polycomb repressive complex 1 (PRC1) that functions as an E3-ubuiquitin ligase that transferring the mono-ubuiquitin mark to the C-terminal tail of Histone H2A at K118/K119 []. PRC1 is also capable of chromatin compaction, a function not requiring histone tails, and this activity appears important in gene silencing []. RING1 interacts with multiple PcG proteins and displays tumorigenic activity[]. It also shows zinc-dependent DNA binding activity. Moreover, RING1 inhibits transactivation of the DNA-binding protein recombination signal binding protein-Jkappa (RBP-J) by Notch through interaction with the LIM domains of KyoT2 []. RING1 contains a C3HC4-type RING-HC finger [].
