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Cell regulation, Stop-go signal - Coggle Diagram
Cell regulation
3 Checkpoints
G2
M
G1
Stop-go signal
External signal
Physical signals
Anchorage dependence (cell must attached to a substrate
density dependence inhibitor: crowded cultured cells stop dividing
EXTERNAL SIGNALs
EXTRACELLULAR SIGNALS
SURVIVAL FACTORS
Suppresing progammed cell death
MITOGENS
Stimulate cell division by triggering a wave of G1/S-cdk activity
GROWTH FACTOR
platelet derived GF (PDGF)
made by platelets
binding of PDGF to cell receptors stimulates fibroblast cell division
other GF
IL2: stimulates T lymphocytes
nerve gf (ngf): promotes neuronal survival and growth
EGF, VEGF,IFG-1,IFG-2
Act on g0,g1
Internal signal
Cyclin and Cyclin-dependent kinases
Kinases: Enzyme activates other proteins via phosphorylation
Cyclin:
Regulatory proteins
Unstable level
Cyclin-dependent kinases
Inactivate until bound to specific cyclin
Constant concentration in the cell
Activity fluctuates with cyclin conc
Different cyclin-cdk complexes trigger different cell cycle steps
G1 cyclins: Cdk4/6/cyclin D
G1/S: CDK2/CyclinE
S-phase: CDK2/cyclin A
M-phase cyclins:Cdk1/cyclin B
