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#CDK1-Cyclin B

3 public questions tagged with this topic.

Cell Cycle Regulation

The mitotic CDK1-Cyclin B complex (MPF) is responsible for:

MPF converts interphase architecture into mitotic state through phosphorylation of hundreds of substrates. Nuclear entry of CDK1-Cyclin B, facilitated by phosphorylation of Cyclin B cytoplasmic retention sequence, allows access to chromatin proteins. Condensin I and II pentameric complexes containing SMC2, SMC4 become phosphorylated at non-SMC subunits CAP-D2, D3, CAP-G, H2, activating ATP-dependent loop extrusion that folds 10nm fiber into 700 nm wide rod chromosomes. Lamins phosphorylated at Ser22 Ser392 disassemble intermediate filament meshwork leading to nuclear envelope breakdown and mer

Ref: Hirano, Condensins and Mitotic Chromosome Architecture, Nat Rev Mol Cell Biol 2012; Alberts et al., Chapter 17, MPF Targets.

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Cell Cycle Regulation

Which complex regulates the G2/M transition?

G2 to M transition represents bistable switch controlled by accumulation of active CDK1-Cyclin B, often termed mitosis-promoting factor. Throughout G2, Cyclin B synthesis steadily rises transcribed by FoxM1 and stabilized, yet associated CDK1 remains inactive due to inhibitory phosphorylations at Thr14 and Tyr15 catalyzed by nuclear Wee1 and cytoplasmic Myt1 kinases occupying ATP-binding pocket. At threshold, dual specificity phosphatase Cdc25B initially and subsequently Cdc25C removes these phosphates. Activating Thr161 phosphorylation by CAK complex CDK7-Cyclin H further boosts activity. Onc

Ref: Morgan, Cell Cycle Control Principles of G2/M Transition, Chapter 3; Alberts et al., Molecular Biology of the Cell, CDK1-Cyclin B Regulation.

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Cell Cycle Regulation

Which of the following is NOT a function of CDK1-Cyclin B?

CDK1-Cyclin B, historically termed Maturation Promoting Factor, orchestrates early mitotic transformations upon nuclear translocation. Its catalytic subunit CDK1 becomes competent after binding Cyclin B, phosphorylation at Thr161 by CAK and dephosphorylation of inhibitory Thr14/Tyr15 by Cdc25C. Once active, it phosphorylates serine-threonine-proline motifs on diverse substrates: lamins A-C at Ser22, Ser392 causing depolymerization of intermediate filament network and nuclear envelope breakdown, condensin subunits Cap-D2, Cap-H2 stimulating chromosome condensation, Golgi matrix proteins GRASP65

Ref: Morgan, The Cell Cycle: Principles of Control, Chapter 3, Mitotic CDK Functions; Nature Reviews, Mitotic Entry and Mitosis.

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