14-3-3 Binding Phosphoproteome Flashcards
How do 14-3-3 proteins bind to proteins?
Through specific tandem pairs of phosphosites
What is the dual-docking conformation?
14-3-3 will act as a singalling intergrator when its two binding sites on a target are phosphorylated by different kinases
How can 14-3-3 binding affect its binding protein?
Can mask a domain
If bound to a disordered region, it can force a disorder-to-order transition which creates a new functional site in the target
Alter the interactions between the domains in a protein
What is the 14-3-3 structure?
As homo- and hetero- dimers with phosphopeptides in them
Where are 14-3-3 located?
In every eukaryotic cell
What is an ‘AND’ gate?
A coincidence detector
Needs 2 inputs before it can generate an output
Name a protein which 14-3-3 masks
Q96RKO CAPICUA
How does 14-3-3 mask Capicua?
HMG is straddled in Capicua
the DNA interaction site is masked since HMG is phosphorylated twice and therefore 14-3-3 bind to and masks it
What is ASK1?
Apoptosis signal-regulating kinase 1
Member of MAP3K5
How does 14-3-3 inhibit MAP3K5?
It is phosphorylated on linker region which binds to the central groove of 14-3-3. This pulls the kinase domain against the back end of 14-3-3 and inhibits the kinase activity since ATP accessibility is removed
What is ZNRF2?
A RING-E3 Ubiquitin ligase
What is the structure of ZNRF2?
It is tethered to the intracellular membrane through its lipid tail
What is the function of ZNRF2?
Facilitates the ubiquitylation of ion channels and regulates the trafficking of ions when it is tethered to the membrane
What phosphorylates ZNRF2?
PKA
PKB
PKC
What does ZNRF2 phosphorylation induce?
14-3-3 binding
What happens when 14-3-3 binds to ZNRF2?
It is soluble and inhibited - dissociated from the membrane and goes into the cytoplasm
What is GNF-2?
Memetic myristoyl
Binds to BCR-Abl myristoyl pocket
How does GNF-2 impact ZNRF2?
It stops ZNFR2 from leaving the membrane, even when phosphorylation has occured
What do the kinases which create phosphosites do and what is specific for their phosphorylation?
Phosphorylate a serine or threonine
They never have a proline in the +1 position
What does insulin do in terms of 14-3-3?
Generates phosphosites for 14-3-3 to bind in the spleen, kidney, pancreas, adipose and gastro
How does insulin drive glucose into skeletal muscles?
Through the translocation of GLUT4 in intracellular vesicles to the plasma membrane
How does 14-3-3 aid GLUT4 translocation in response to insulin?
AS160 is phosphorylated and 14-3-3 docks onto it -> inhibits Rab-GAP activating protein -> gets loaded with GTP -> Activate Rab bring GLUT4 to the plasma membrane
What is AS160?
a 14-3-3 binding protein which has an active site of Rab-GAP
What are Rabs involved in?
Specific vesicle trafficking events
what disease is associated with AS160 mutation?
Type 2 diabetes
What is the phenotype of AS160 mutated type 2 diabetes? And what does this suggest?
Heavy pigmentation behind the neck and knees
Involved in trafficking melanin containing vesicles in the skin cells
What happens when there is no amino acids in the heart available for it to function?
The heart can use glucose from AS160
What is the function of SPEG?
Can bind to SERCA2A and phosphorylates it in response to insulin
Where is SPEG found?
The heart
What is SERCA2A?
A calcium pump
What happens if SPEG is mutated at phosphorylated sites?
Impaired Ca2+ reuptake into SR and cardiac dysfunction
What processes does insulin-induced 14-3-3 binding downregulate?
Lipolysis
Gluconeogenesis
Autophagy
What processes does insulin-induced 14-3-3 binding upregulate?
Glucose uptake Amino acid uptake K+ and PO43- uptake Glycogen synthase Glycolysis in the heart Lipid synthesis Esterification of fatty acids
What physiological functions does insulin-induced 14-3-3 binding control?
Arterial muscle tone relaxation
Endothelial permeability and inflammation
Cytoskeletal remodelling
HCl production by parietal cells of the stomach
Bone remodelling
Feedback control of pancreatic function
Brain functions
If you have diabetes, what are common chronic secondary diseases?
renal disease
cardio myopathy
How does the brain respond to insulin?
A huge dephosphorylation of 14-3-3 binding proteins
Inhibits cerebral PKA
What protein in the brain is associated with Alzheimer’s?
TAU
How can diabetes cause Alzheimer’s?
An increase in the insulin levels causes neurofibril tangles in the brain
In fasted animals, what does 14-3-3 bind to?
PhosphoSer?
PhosphoSer948
Ser858 is phosphorylated in fasted animals, what does this do?
Activates Rac1 GAP domain
In fasted animals, what does phosphoFAM122A - 14-3-3 complex do?
It is translocated to the nucleus, which inhibits dephosphorylation of TAU by PP2A
How is sleep linked to insulin resistance?
1 night of bad sleep can lead to insulin resistance to a higher degree compared to a high fat diet for several months
