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| CLN1 | G1 cyclin: activates CDC28 kinase to promote the G1 to S phase transition; CLN-CDC28 complex enhances ubiquitin-mediated proteolysis of SIC1 by phosphorylation, regulates START-related events: budding, spindle-pole-body duplication, and DNA synthesis, and homologous with CLN2 |
| CLN2 | G1 cyclin: activates CDC28 kinase to promote the G1 to S phase transition; CLN-CDC28 complex enhances ubiquitin-mediated proteolysis of SIC1 by phosphorylation, regulates START-related events: budding, spindle-pole-body duplication, and DNA synthesis, and homologous with CLN1 |
| CLN3 | G1 cyclin: activates CDC28 kinase to promote the G1 to S phase transition and regulates transcription of CLN1 and CLN2 |
| Cyclins | CLB1 | G2 cyclin: activates CDC28 kinase to promote the transition from G2 to M phase, promotes spindle elongation during mitosis, negatively regulates SBF-mediated transcription, and homologous with CLB2 |
| CLB2 | G2 cyclin: activates CDC28 kinase to promote the transition from G2 to M phase, promotes spindle elongation during mitosis, negatively regulates SBF-mediated transcription, and homologous with CLB1 |
| CLB5 | G1/S cyclin: activates CDC28 kinase to promote initiation of DNA synthesis, inactivated by SIC1, negatively regulates CLN-CDC28 complex formation, forms mitotic spindles in association with CLB3 and CLB4, and homologous with CLB6 |
| CLB6 | G1/S cyclin: activates CDC28 kinase to promote initiation of DNA synthesis, inactivated by SIC1, negatively regulates CLN-CDC28 complex formation, forms mitotic spindles in association with CLB3 and CLB4, and homologous with CLB6 |
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| CDC | CDC6 | ATP-binding protein required for DNA replication, component of the pre-replicative complex (pre-RC) which is required for MCM2-7 DNA association |
| CDC28 | Cyclin-dependent kinase: alternately associates with G1 cyclins and G2/M cyclins, regulates spindle-pole-body duplication, budding, SIC1 proteolysis in association with CLN1-3, regulates DNA replication in association with CLB5-6, and regulates spindle assembly, inactivation of CLN transcription through repression of SBF transcription factor in association with CLB1-2 |
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| MCM1 | Regulates expression of CLB1, CLB2, BUD4, SWI5 in M phase: CLN3, SWI4, CDC6 at M/G1 transition |
| SWI4 | Transcription cofactor, forms complex with SWI6 and regulates transcription of CLN1-2; activity initiated by CLN3-CDC28, repressed by CLB2-CDC28 |
| Transcription factors | SWI5 | Activates transcription of SIC1 and CDC6 at the M/G1 phase boundary and in G1 phase; localization to the nucleus occurs during G1, regulated by CDC28-mediated phosphorylation |
| SWI6 | Transcription cofactor: forms complexes with DNA-binding proteins SWI4 and MBP1 to regulate transcription at the G1/S transition and regulates transcription of CLN1-2, CLB5-6; localization regulated by phosphorylation; transcriptional activity initiated by CLN3-CDC28 complex, repressed by CLB2-CDC28 complex |
| MBP1 | Transcription cofactor: forms complex with SWI6 and regulates transcription of CLB5-6 |
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| Inhibitors | SIC1 | Inhibits CLB5/6-CDC28 complex formation, inhibits G1/S transition, downregulates CLB-CDC28 activity in late stages of mitosis, targeted for ubiquitin-mediated proteolysis by CLN-CDC28 |
| CDH1 | Activates anaphase promoting complex/cyclosome (APC/C) and directs ubiquitinylation of cyclins, cell division cycle genes |
| CDC20 | Activates anaphase-promoting complex/cyclosome (APC/C) and directs ubiquitination of CLB1-4, PDS1 |
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