Post translational modifications Flashcards
O2, H202/ OH radical target what residues?
What is this called?
Cys/Met
free radical oxidation
Carbonyls/aldehydes/ketones —> targets?
glycation
Lys/Arg/Cys
His
NO—> ?
?’s targets
what is this called?
ONOO-, NO2
nitration
Tyr
HS2–> ?
?’s targets
What is this called?
HS-
sulfhydration
cys
Succination –>
fumerate (-OOC-C=C-COO)
Cys
Phosphorylation —>
Donor group (DG) Target (TG)
DG: ATP
TG: Ser, Thr, Tyr
Acetylation —>
DG
TG
DG: Acetyl Co-A
TG: Lys-Argq
Methylation —>
DG
TG
DG: SAM
TG: Lys-Arg-His
ADP-ribosylation
DG
TG
DG: NAD+
TG: Arg-Glu-Asp
Glycosylation
DG
TG
UDP
DG: N-lingages, ASP
DG-: O-linkages (Set/Thr/Tyr)
Small molecule modifications (glycosylation)
Lys–> OH-Lys
Pro–> OH-Pro
THEN glycosylation occurs at these hydroxyl sites
collagen molecules
Myristoylatiln
DG
TG
DG: Co-A
TG: N-terminal Glu
Palmitaylation
DG
TG
DG: Co-A
TG: Cys
Farnesylation
DG
TG
…also known as
DG: Co-A
TG: Cys
prenylation
Ubiquination
DG: ubiquinone
TG: Lys
degradation
Sumoylation
DG
TG
DG: SUMO
TG: Lys
translocation and gene expression
small unbiquitine like modifier
proteins that get tagged on to other proteins
ISG
DG
TG
DG: ISG
TG Lys
gene expression and translocation
interferron stimulated gene (product)
proteins that get tagged on to other proteins
Oxidation: what does it do? With what? Targets?
Modifies proteins
O2- superoxide radical
H2O2/OH– hydrogen peroxide —> hydroxyl radical
His/Cys/Met/Tyr/Thr
Glycation: what does it do? With what? Targets?
Modifies proteins
Carbonyls (aldehydes/ketones)
Targets: lys, arg, cys
irreversible
ROS groups include
oxidation and glycation
NOS groups
nitration (tyr) and nitrosylation (cys)
ONOO, NO
Death Cascade involving GAPDH steps
GAPDH is a glycolytic enzyme
- translocation
- dna repair
- apoptosis
- telomere maintenance
modifications of GAPDH
N-acetylation
lys-117, 226, 251
modifications of GAPDH
s-nitrosylation
cys-152 modified
Modifications of GAPDH
O-GlcNacylation
Thr-229
What do modifications to GAPDH do?
Modifications promote susceptibility of GAPDH to translocating into the nucleus to be destroyed
Protein Oligomerization
Stable tetramer metastable dimer unstable dimer unstable chain
Which of these is translocated into the nucleus?
the metastable dimer form
What causes GAPDH to be translocated into the nucleus?
GAPDH is a glycolytic enzyme in the glycolysis pathway
While doing it’s job, something happens to injure the cell
Describe pathway to apoptosis
GAPDH (glycolytic) –> cell injury causes modification (acetylation, glycolation, nitrosylation) –> instability of enzyme –> GAPDH translocated into nucleus –> apoptosis
E1, E2, E3 enzymes involved in what?
ISG/SUMOLATION/UBIQUINATION
E1 = activation of small protein (such as ubiquitone)
E2 = transfer event (temporarily)
E 3= ligation (small protein is attached to target)
SUMOLATION/ISG degradation or other?
other, such as gene expression
GAPDG signals the cascade leading to apoptosis
O-Glc-Nacylation targeting Thr-229
S-nitrosylation targeting Cys- 152
N-acetylation targeting Lys 117, 227, and 251
NMDA receptos do what
cells that excite neuron
Siah1
E3 ubiquination ligase responsible for translocating modified GAPDH into cell
Sulfhydryl Oxidation of GAPDH occurs at
Cys 152
Thr-229
O-GlcNacylation
Cys-152
s-nitrosylation
Lys-117, 227, 251
N-acetylation
s-thiolation occurs where
Cys-152
thiol–> sulfenic acid –> sulinic acid –> sulfonic acid –>
what is this?
–> destroyed
levels of oxidation
thiolation of Cys-152 does what, how?
protects it by inactivating it. the protein with the cys-152 is inactive. group can reversible thiolated/recovered
Tdh is the
yeast equivalent of GAPDH
Under basal levels of oxidation, tdh3 is
kept s-thiolated to protect it
high levels of oxidative stress do what to tdh?
tdh2 becomes inactivated due to chemical modifications
in what state is tdh3 maintained most of the time? tdh2?
tdh3 is glutathionated (inactivated)
tdh2 is active
What happens under intense oxidation in terms of tdh2 and 3?
tdh3 is thiolated and protected but tdh2 isn’t. under immense oxidative stress tdh2 is destroyed. the tdh3 can then be converted into the active form rapidly
How do cells compensate for high oxidative stress?
tdh2 (active) becomes inactivated due to chemical modifications, so tdh3 (inactive) is converted into the activated form
how is tdh3 activated?
the glutathione is cleaved
Tdh3-glutathione vs Tdh3
inactivated to activated
where does the tdh3 activation occur as an example?
in neurons
how is hydrogen sulfide derived?
enzymatically from metabolism in pathways in cells
free radical oxygen targets
cys/met
Nitrosylation ?
exactly the same thing as nitration
NO–> ONOO, NO2
cys
