CellSig5 - 19 Flashcards
What generally activates proteins?
Addition of phosphate groups
What catalyses dephosphorylation?
Phosphatase
What are the general kinase targets?
Sugars, nucleic acids, lipids, proteins
Where does protein phosphyrlation usually occur?
On amino acids with hydroxyl-containing side chains, either serine/threonine or tyrosine
What part of phosphorylation is actively regulated?
Turning on by kinases
How is the addition of phosphate groups visualised?
Addition of gamma-32-p-ATP, then use of radiation counter or autoradiography
What secondary messengers are controlled by Ca?
MLCK - myosin light chain kinase
What secondary messengers are controlled by nucleotides?
cAMP/cGMP-dependent kinase (PKA/PKG, or A/G kinase)
What secondary messengers are controlled by lipids?
Protein kinase B (PKB aka Akt) or C (PKC requires Ca)
What controls secondary messengers?
Ca, nucleotides, lipids
What controls phosphorylation?
MAPKs - mitogen activated protein kinases
What controls autophosphorylation?
TGFb signalling
What is a consensus phosphorylation site?
The only context in which any Ser, Thr or Tyr residue can be phosphrylated
Outline regulation of cell cycle
Cdk1 + M-cyclin > inactive M-Cdk + Cdk-activating kinase + Cdk-inhibitory kinase > inactive M-Cdk + pCdc25 > active M-Cdk
Outline feedback of the regulation of cell cycle
Active M-Cdk promotes Cdc25 phosphorylation and inhibits Cdk-inhibitory kinase
Characterse cell cycle regulation feedback
Positive feedback
Outline the vertebrate ERK-MAP kinase cascade
Grb2 > SOS > Ras > Raf > ERK > multiple substrates
What do scaffold proteins do?
Spatially regulate kinase cascades to prevent cross-talk (some kinases are used in multiple cascades)
Characterise phosphatases
Broader substrate specificity than kinases and are probably not as tightly regulated as kinases
