G1 - First Gap Phase

Mammalian Protein(s) Complete Name Basic Cell Cycle FunctionCAK CDK-Activating Kinase Involved in CDK-Cyclin activation; Phosphorylates T160/161 of CDKs CDC25A Cell Division Cycle 25A Dual-specificity phosphatase that removes inhibitory phosphates at T14 and Y15 of CDKs

CDK2-Cyclin E Cyclin-Dependent Kinase 2-Cyclin E CDK-Cyclin complex activated at the G1/S transition; Phosphorylates Rb and other substrates to promote S phase

CDK4/6-Cyclin D Cyclin-Dependent Kinase 4/6-Cyclin D CDK-Cyclin complexes activated in G1 to promote cell cycle progression; Phosphorylate Rb and other substrates

CIP/KIP CDK-Interacting Protein 1/ CDK Inhibitory Protein 1

Family of proteins that includes p21, p27, and p57 which bind CDK/Cyclin complexes in the nucleus to inhibit CDK activity

E2F/DP E2 Promoter Binding Factor/ Dimerization Partner

Protein complex that activates the transcription of genes whose products are important for promoting DNA replication

Rb Retinoblastoma Protein Hypophosphorylated form recruits histone deacetylase to the promoters of E2F-regulated genes to inhibit their expression; Rb phosphorylation allows E2F-DP activity

Wee1 Wee1 Protein kinase that negatively regulates CDK-Cyclin complexes by inhibitory phosphorylation of CDKs at Y15

S phase - DNA ReplicationMammalian Protein(s) Complete Name Basic Cell Cycle FunctionPre-Replication Complex (Pre-RC)

CDC6 Cell Division Cycle 6 Replication licensing factor involved in loading the MCM2-7 helicase complex onto origins (ORI); Inhibits re-replication

CDT1 CDC10-Dependent Transcript 1 Replication licensing factor involved in loading the MCM2-7 helicase complex onto origins; Inhibits re-replication

Geminin Geminin Inhibitor of CDT1; Prevents origin licensing from S phase to metaphase by blocking the loading of the MCM2-7 helicase complex

MCM2-7 Minichromosome Maintenance 2-7 Hexameric protein complex that acts as a helicase to unwind DNA at origins of replication

MCM10 Minichromosome Maintenance 10 Regulates replication initiation and elongation by recruiting CDC45 and DNA pol a/Primase to origins; Stabilizes DNA pol a/Primase

ORC Origin Recognition Complex Hexameric protein complex that acts as a scaffold for the assembly of multiprotein pre-RCs at origins of replication

Origin ActivationCAK CDK-Activating Kinase Involved in CDK-Cyclin activation; Phosphorylates T160/161 of CDKsCDC7/DBF4 Cell Division Cycle 7/Dumbell Former 4 CDC7: Protein kinase required for the initiation of DNA replication; DBF4: Regulates CDC7 activity CDC25A Cell Division Cycle 25A Dual-specificity phosphatase that removes inhibitory phosphates at T14 and Y15 of CDKs

CDC45 Cell Division Cycle 45 Helicase co-factor essential for replication initiation and elongation; Loading at origins is required for the association of DNA polymerase a/Primase

CDK2-Cyclin E/A Cyclin-Dependent Kinase 2-Cyclin E/A CDK-Cyclin complexes required for origin activation in S phaseOrigin Unwinding

DNA Pol a/Primase DNA Polymerase a/Primase Synthesizes primers de novo to initiate DNA replication

RPA Replication Protein A Heterotrimeric protein complex that binds and stabilizes single-stranded DNA (ss-DNA) generated during replication or as a result of DNA damage

ElongationDNA Ligase DNA Ligase Ligates Okazaki fragments together during lagging strand replicationDNA Pol d/e DNA Polymerases d and e DNA polymerases involved in elongation of a primed strand during leading and lagging strand replicationFEN-1 Flap Endonuclease-1 Removes the 5’ single-stranded flap formed by primer displacement during lagging strand replicationPCNA Proliferating Cell Nuclear Antigen Processivity factor for DNA polymerase d; Loaded onto DNA by RFCRFC Replication Factor C Clamp loading complex; Loads PCNA onto DNA

G2 - Second Gap PhaseMammalian Protein(s) Complete Name Basic Cell Cycle Function

14-3-3 14th DEAE elution fraction and 3.3 migration pattern Sequesters CDC25s or CDK1-Cyclin B in the cytoplasm to inhibit the G2/M transition

CAK CDK-Activating Kinase Involved in CDK-Cyclin activation; Phosphorylates T160/161 of CDKs

CDC25A,B,C Cell Division Cycle 25A, B, C Three different dual-specificity phosphatases that promote the G2/M transition by removing inhibitory phosphates from CDK1 at T14 and Y15

CDK1 - Cyclin B (CDC2) Cyclin-Dependent Kinase 1-Cyclin B CDK-Cyclin complex required for the G2/M transition; Phosphorylates multiple substrates to promote mitosisC-TAK1 CDC25C-Associated Kinase 1 Protein kinase that negatively regulates CDC25C to inhibit the G2/M transition

Myt1 Membrane-Associated Tyrosine- and Threonine-specific CDC2 Inhibitory Kinase

Protein kinase that negatively regulates cytoplasmic CDK1-Cyclin B by inhibitory phosphorylation of CDK1 at T14 and Y15

Plk1 Polo-like Kinase 1 Protein kinase that phosphorylates CDC25 and Cyclin B to promote their nuclear translocation at the mitotic transition; Negatively regulates the Myt1 and Wee1 kinases

Wee1 Wee1 Protein kinase that negatively regulates CDK-Cyclin complexes in the nucleus by inhibitory phosphorylation of CDKs at Y15

M phase - MitosisMammalian Protein(s) Complete Name Basic Cell Cycle FunctionChromosomal Passenger Complex (CPC)

Aurora B Aurora BEnzymatic core of the CPC; Mitotic centromere kinase that ensures proper chromosome alignment; Stabilizes microtubule-kinetochore attachments; Required for lack of tension checkpoint response; Regulates cytokinesis

Borealin Borealin Promotes binding of Survivin and INCENP in the CPC

INCENP Inner Centromere Protein Stabilizes the CPC; Regulates Aurora B activation

Survivin Survivin Localizes the CPC to centromeres or the central spindle; Involved in spindle assembly checkpoint activation; Required for the progression of cytokinesis

Mitotic Checkpoint Complex (MCC)

APC/C Anaphase Promoting Complex/Cyclosome E3 ubiquitin (Ub) ligase that targets Cyclin B and Securin for degradation leading to sister chromatid separation in anaphase and mitotic exit

Bub-1 Budding Uninhibited by Benzimidazoles 1 Associates with unattached kinetochores or kinetochores lacking tension; Recruits Bub-3 and BubR1 to inhibit CDC20 and APC/C activity

Bub-3 Budding Uninhibited by Benzimidazoles 3 Localizes Bub-1 and BubR1 to kinetochores

BubR1 Budding Uninhibited by Benzimidazoles R1

Associates with unattached kinetochores or kinetochores lacking tension; Binds CDC20 to inhibit the Ub ligase activity of the APC/C

CDC20 Cell Division Cycle 20 Activator and substrate adaptor of the APC/C

CENP-E Centromere Protein E Involved in the capture and stabilization of spindle microtubules by kinetochores

MAD1 Mitotic Arrest Deficient 1 Associates with unattached kinetochores; Recruits MAD2 to inhibit CDC20 and APC/C Ub ligase activity

MAD2 Mitotic Arrest Deficient 2 Associates with unattached kinetochores; Binds to CDC20 to inhibit the Ub ligase activity of the APC/C

Sister Chromatid Separation

CENP-A Centromere Protein A Histone H3 variant involved in centromere-kinetochore formation

Cohesin Complex Cohesin Complex Protein complex that holds sister chromatids together

MCAK Mitotic Centromere-Associated Kinesin Microtubule depolymerizing activity; Contributes to the correction of defective kinetochore attachments

Securin Securin Inhibits Separase to prevent the cleavage of Cohesin and sister chromatid separation

Separase Separase Protease that cleaves Cohesin allowing sister chromatids to be pulled to opposite poles in anaphase

RnDSy-lu-2945

Regulation of the Cell Cycle and DNA Damage-Induced Checkpoint Activation

NOTE: This poster conveys a general overview and should be considered neither comprehensive nor definitive. The details of this information are understood to be subject to interpretation. © R&D Systems 2009, 2015

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CDK1Cyclin B

CDK1

Cyclin A

CDK2

Cyclin E

CDK2

Cyclin A

CDK4/6Cyclin D

G1S

G2M

Myt1 Plk1

Plk1

Plk1

C-TAK1

Positive Feedback

Loop

CDK1Cyclin B

CDK1Cyclin B

CDK1 Cyclin B

CDK1 Cyclin B

CDK1

Cyclin B

(Inactive)

(Inactive)

(Inactive)

(Active – Prophase)

(Active – Prophase)

CDC25A,B,C Phosphatase

14-3-3

Import(Prophase)

Export(Prophase)

CDC25A,B,C Phosphatase

(Active)

CDC25A,B,C Phosphatase

(Active)

CDK1Cyclin B

CAK

CAK

Mitotic Events

Wee1

Cytoplasmic Substrates

Nuclear Substrates

G2/M Checkpoint

Stalled Replication Forks/Long Stretches of ss-DNA

Slow S Phase Progression

Recovery of Stalled Replication Forks

S Phase Delay

SMC1SMC1

FANCD2

FANCD2

Inhibition of New Origin Firing

Chk1Chk2 Chk1Chk2

Ub-mediated Degradation

BRCA1

BRCA1

ATM

MDC1

53BP1 γ-H2AX

BRCA1

IR

Mre11

Mre11

Mre11

Rad50

Rad50

Nbs1

Nbs1

Nbs1

RPA

CDC45

MCM2-7

MCM10

ATRIP

Rad9-Rad1-Hus1RFC2-5

Rad17Claspin

ATR

Ubiquitin

ORI

CDC6 CDT1MCM2-7MCM2-7

MCM10MCM10

DNA Pol α/Primase

CDC45

DNA Pol α/Primase

Slow S Phase Progression

TopBP1

CDC25A Phosphatase

CDK2

Cyclin E/A

Intra-S-Phase Checkpoint

UV

ATRIP

Inhibition of Replication Origin Firing

Maintenance of G1/S Arrest

ATM

MDC153BP1

γ-H2AX

BRCA1

IR

Chk1Chk2

Ub-mediated Degradation

ORI

ORC

ORC

CDC6 CDT1

DNA Pol α/Primase

MCM2-7

MCM2-7

MCM10MCM10

Rad9-Rad1-Hus1

RFC2-5

Rad17Claspin

p53 p53

p21 p21

MDM2 MDM2

p53 p21p53 p21

CDK2

Cyclin E

CDC45

Mre11Rad50

Nbs1Rad50

TopBP1

UbiquitinCDC25A Phosphatase

ATRG1/S Checkpoint

CDC25A,B,C Phosphatase

p38

Wee1(↑Activity)

Wee1(↑Activity)

p2114-3-3σGADD45α

G2 M

UV

ATRIP

Maintenance of G2/M Arrest

ATM

MDC1

53BP1γ-H2AX

BRCA1

IR

Chk1Chk2

Rad9-Rad1-Hus1

RFC2-5

Rad17

p53 p53

p21

MDM2 MDM2

p53p53

p2114-3-3σGADD45α

Mre11Rad50

Nbs1

TopBP1

ATR

MAPKAPK-2

14-3-3σ

GADD45αGADD45α

p21

14-3-3σ

CDK1

Cyclin B

Inhibition of M Phase

14-3-3 Sequestration or Ub-mediated

Degradation

14-3-3 Sequestration or Ub-mediated

Degradation

Claspin

CIP/KIP (p21, p27, p57)

(Inactive)

Positive Feedback

LoopCDC25A

Phosphatase(Active)

CDK2Cyclin E

CDK2Cyclin E

(Active)CDK2

Cyclin E

(Active)

CDK4/6

Cyclin D

EGF REGF R

EGF

EGF

EGF R

Jak

STAT

STAT dimer

Src

SOS

PKC

IP3

RAF MEK1/2

ERK1/2

Ca2+ IP3 Receptor

MKP

RAS

DAG

PIP2

PLCγ

Gene Transcription

MycELK-1

Rb

E2F DPRb

EGF

EGF R

EGF

EGF R

PIP2

PIP3

GAB-1

GAB-2

SHIP

PTEN

PDK-1Akt

GSK-3 TSC1/2TOR

p70 S6KProtein TranslationPI 3-Kinase

PP2A

S6

Cyclin DCyclin ECDC25A Phosphatase Cyclin E

Other S Phase Genes

1

2

Wee1

CAK

EGF

CAK

Promotes ReplicationOrigin Firing

Geminin

Origin Activation

CDC25A Phosphatase

(Active)

RPA

RPA

RPA

DNA Pol α/Primase

DNA Pol α/Primase

DNA Pol δ/ε

DNA Pol δ/ε

DNA Pol δ/ε

CDC45

MCM2-7MCM10

RPA

RFC

RFC

PCNA

PCNA

Elongation

(Lagging Strand)

DNA Pol α/Primase

ORI

ORCCDC6 CDT1

MCM2-7MCM2-7

MCM10MCM10

ORI

ORC

CDC6 CDT1 MCM2-7

MCM2-7MCM10

MCM10

MCM10

Leading Strand

Lagging Strand

(Active)

Unwinding

Pre-RC (G1)

CDK2

Cyclin E/A

CDC45CDC7

DBF4

CAK

CDC45Direction of

Fork Movement

MCM2-7

DNA Ligase

FEN-1

RFCDNA Ligase

FEN-1

Chromosomal Passenger Complex

INCENP

Borealin

Survivin Aurora B

MCAK

CENP-EBub-1Bub-3

BubR1MAD1MAD2 CDC20

APC/C

Separase

Securin

Ubiquitin

Cyclin BCDK1

Cohesin Complexes

Bipolar Microtubule

Stabilization

Proteasome

Kinetochore

CENP-A

Mitotic Checkpoint

Complex Chromatin Condensation

Metaphase Plate

Spindle Fibers (Microtubules)

Sister Chromatids

Centromere

Centrioles

Cleavage Furrow

Decondensing Chromosomes

Contractile ring (actin)Contractile Ring

(Actin)

Mitotic CheckpointProtein Recruitment

}

Spindle Assembly Checkpoint

ProphaseMetaphase

Anaphase

Telophase (Cytokinesis)

Mammalian Protein(s) Complete Name Basic Checkpoint Function

Sensors: Proteins that recognize and bind to damaged DNA to initiate signal transduction pathways that inhibit cell cycle progression and promote DNA repair or apoptosis.

Rad9-Rad1-Hus1 (9-1-1 Complex) Radiation Sensitive 9-Radiation Sensitive 1-Hydroxyurea Sensitive 1 Heterotrimeric DNA-binding complex that coordinates checkpoint signaling and DNA repair

g-H2AX Histone H2A variant X Recognizes and binds to DNA double-strand breaks (DSBs)

Mre11-Rad50-Nbs1 (M/R/N Complex) Meiotic Recombination 11-Radiation Sensitive 50-Nijmegen Breakage Syndrome 1 Recruits and activates ATM at DNA DSBs

Rad17 Radiation Sensitive 17 Loads the 9-1-1 complex onto damaged DNA along with RFC2-5

RFC2-5 Replication Factor C 2-5 Loads the 9-1-1 complex onto damaged DNA along with Rad17

Mediators: Scaffolding proteins that form multiprotein complexes at sites of DNA damage to recruit transducers and maintain checkpoint activation.

53BP1 p53 Binding Protein 1 Scaffolding protein at DNA DSBs; Recruits other checkpoint/repair proteins

BRCA1 Breast Cancer 1 Scaffolding protein at DNA DSBs; DNA repair and recombination

Claspin Claspin Bridges ATR and Chk1 to facilitate Chk1 activation

MDC1 Mediator of DNA Damage Checkpoint 1 Scaffolding protein at DNA DSB sites; Recruits other checkpoint/repair proteins

TopBP1 Topoisomerase Binding Protein 1 Implicated in ATR activation; Binds to Rad9 in the 9-1-1 complex to promote ATR-mediated Chk1 phosphorylation

Transducers: Kinases that are activated to transmit damage signals to effector molecules in the cell.

ATM Ataxia Telangiectasia-Mutated Phosphorylates multiple substrates in response to DNA DSBs

ATR-ATRIP ATR: ATM and Rad3-related; ATRIP: ATR-Interacting Protein ATR: Phosphorylates multiple substrates in response to DNA damage that induces long stretches of RPA-coated ss-DNA such as stalled replication forks, or UV-induced DNA damage; ATRIP: Interacts with RPA and regulates the recruitment of ATR to sites of DNA damage

Chk1 Checkpoint Kinase 1 Kinase activated by ATR via phosphorylation; Phosphorylates and inactivates CDC25s

Chk2 Checkpoint Kinase 2 Kinase activated by ATM via phosphorylation; Phosphorylates and inactivates CDC25s

p38 MAPK p38 Mitogen-Activated Protein Kinase Activated by different types of DNA damage; Implicated in the G2/M checkpoint

MAPKAPK-2 Mitogen-Activated Protein Kinase-Activated Protein Kinase 2 Activated by p38 MAPK; Implicated in the G2/M checkpoint

Effectors: Proteins that can directly prevent cell cycle progression when activated or inhibited by transducers.

p53 p53 Transcription factor; Primary regulator of cell cycle arrest and DNA repair, or initiation of apoptosis

BRCA1 Breast Cancer 1 Implicated in the Intra-S-phase checkpoint; Interacts with FANCD2 to mediate recombinational repair of DNA damage generated by IR, crosslinking, or stalled replication forks

CDC7/DBF4 Cell Division Cycle 7/Dumbell Former 4 CDC7: Protein kinase required for origin activation; DBF4: Regulates CDC7 activity

CDC25A Cell Division Cycle 25A Protein phosphatase required for CDK dephosphorylation and activation; Implicated in the G1/S, Intra-S-phase, and G2/M checkpoints

CDC25B Cell Division Cycle 25B Protein phosphatase required for CDK dephosphorylation and activation; Implicated in the G2/M checkpoint

CDC25C Cell Division Cycle 25C Protein phosphatase required for CDK dephosphorylation and activation; Implicated in the G2/M checkpoint

CDKs Cyclin-Dependent Kinases Protein kinases required for progression through each stage of the cell cycle

FANCD2 Fanconi Anemia Complementation Group D2 Implicated in the Intra-S-phase checkpoint; Interacts with BRCA1 to mediate the resolution of DNA crosslinks and stalled replication forks

Mre11-Rad50-Nbs1 (M/R/N Complex) Meiotic Recombination 11-Radiation Sensitive 50-Nijmegen Breakage Syndrome 1 Implicated in the Intra-S-phase checkpoint as both an activator of ATM and an effector; Inhibits origin firing after specific types of DNA damage by an unknown mechanism; DNA end- processing to facilitate DNA repair or recombination

SMC1 Structural Maintenance of Chromosomes 1 Implicated in the Intra-S-phase checkpoint as part of the ATM-Nbs1-SMC1 branch; Unknown mechanism to inhibit origin firing after specific types of DNA damage; Sister-chromatid cohesion and recombination

Regulators of Cell Cycle Progression Cell Cycle Checkpoint Proteins

Sensors

Mediators

Transducers

Effectors

Sensors

Mediators

Transducers

Effectors

Sensors

Mediators

Transducers

Effectors

Sensors

Mediators

Transducers

Effectors

Activating Phosphorylation Inactivating PhosphorylationP P