Lecture 15 Signal Transduction Part 2 Flashcards
Phosphorylation
addition of phosphate group to a molecule, usually a protein
Protein kinases are enzymes that are the effectors of __________ and catalyze the _____________ from ATP to specific acids on proteins
phosphorylation, transfer of phosphate group
Proteins are phosphorylated primarily on what residues?
Serine, Threonine and tyrosine.
Give 3 examples of serine and threonine kinases.
PKA, PKC, CaMKII
What are protein phosphatases and what do they do?
cleave phosphate from target molecule–dephosphorylate
Binding of the second messenger removes _________ and allows catalytic domain to be activated.
autoinhibition
What do catalytic subunits do?
transfer phosphate group to target proteins
Catalytic subunits are being kept inactive by __________
regulatory subunits (autoinhibition)
Many kinases are regulated by ___________ in the activation loop.
phosphorylation
Name the steps to the phosphorylation of the ERK2 activation loop
Phosphorylation on threonine and tyrosine
Phospho-thr 183 contacts alphaC and promotes active confirmation
Phospho-thr183 promotes ERK2 dimerization via changes in c terminal extension
Break time! https://www.youtube.com/watch?v=PPQNbTPb-F0
:)
Name the 4 stimuli that kinases can be activated by.
CaMKII (calcium)
PKC (lipids and calcium)
TRKS (ligands)
PDK1/AKT (lipids)
__________ by binding to the regulatory subunits and causing them to release active catalytic subunits.
cAMP activates PKA
Catalytic subunits phosphorylate _______ and ________ residues of target proteins.
serine, threonine
Phosphorylation usually results in ________ of the substrate protein.
activity change
When cAMP concentration rises, it binds on the 2 regulatory subunits, which leads to release of catalytic subunits. These then transfer ATP to protein substrates and serine threonine. What activation cycle is this describing?
PKA activation
Downregulation of PKA occurs by a feedback mechanism. What is this mechanism called and what’s its function?
PDE, converts cAMP to AMP, reducing cAMP that can activate PKA, therefore, PKA is controlled by cAMP
_____ causes PKC to move from cytosol to the membrane where it binds calcium and another phospholipid.
DAG
What process relieves autoinhibition, enabling PKC to phosphorylate proteins?
the DAG process
________ link DAG and calcium signals to downstream targets.
PKS isoforms
Calmodulin activates CaMKII by doing what?
displacing inhibitory domain from the catalytic subunit.
Describe the induction and early phase of mechanisms underlying LTP?
Rise in postsynaptic Ca2+ and acts as 2nd messenger, activating CaMKII and PKC
Maintenance of LTP is due to insertion of ______ into the postsynaptic membrane.
AMPA-Rs (causes increased response to glutamate)
MAPK regulate what and why are they special?
gene expression, they are kinases that are regulated by other kinases.
Changes in gene expression and protein synthesis brought about by the persistent activation of protein kinases activated during early LTP is known as what?
Late LTP
Break time!
https://www.youtube.com/watch?v=U-aVkMClvBs
:)
Upon activation, ERK phosphorylates ________ leading to synthesis of new proteins.
transcription factors (BREB)
Protein phosphatases are the primary effectors of dephosphorylation. What to they act in opposition to?
Act in opposition to protein kinases.
T/F: Kinases add phosphates and phosphotases remove them
True
T/F: Several proteins use the same phosphorylation sites for activation and inhibition.
False, they have separate sites.
What allows for PNA polymerase to assemble on DNA promotor region and to begin transcription?
transcription factors
In RNA polymerase activity: activators ________ and repressors _________ gene expression.
enhance, decrease
CREB binds to what to increase/decrease transcription of genes?
cAMP response elements
T/F: CREB is normally unphosphorylated. Its phosphorylation potentiates transcription
True
