Intro Flashcards
Post translational modification of proteins
Where?
When?
Covalent addition/ cleavage of proteins
On amino acid chain/ terminal
After protein biosynthesis
3 germ layer types
Endoderm
Mesoderm
Ectoderm
How is pleuropotency established maintained and modulated ?
Cell signalling networks
PTM and proteome diversity extending function and stability
Reversible/ irreversible structure alteration
Types of PTM
Phosphorylation
Glycosylation
Methylation
Acetylation
Disulphide bond
Phosphorylation
+/- phosphate to ser/thre/tyr
Reversible
Conformational protein change
Enzyme activation/ deactivation
Glycosylation
Attaches sugar to N/O in an amino acid side chain cov linked via glycosidic
Methylation
+ methyl group at Lys/Arg residues
Acetylation
+ acetyl group to N-terminus of protein / lys res via coA
Donated by acetyl coA
Enzymatic / non-enzymatic > (de)acetylase
Co/post TM
Disulphide bond PTM
Cov links S atoms of 2 cys res
Cleavage PTM example
Translation/ translocation
Folding/ oxidation/ signal peptide cleavage
ER export/ Golgi transport/ vesicle packaging
Protease cleavage > C-peptide liberation
Carboxypepfidas E > mature insulin
Covalent addition PTM
+ new functional groups
Cell signalling and reaction enables
Response to environmental stress
Phosphate charge interaction
2 negative charges
(Enzyme activation)
Enzyme deactivation phosphorylation
Can mask binding site
Protein kinases
Enzymes catalysing phosphate transfer from a high energy donor
Unidirectional reaction
P from ATP
Phosphatase
Enzyme catalysing phosphate removal from substrate via hydrolysis of phosphoric acid monoesters > Phosphate ion + molecule w free hydroxyl
Glycosylation
Carb covalent binding to functional group on protein via glycosidic bond
Glycosylation function
Correct folding / protein stability/ cell adhesion/ immune response/ hormone activity/ embryonic development
Glycosylation location
On dolichol
5 Glycosylation types
O-linked (on ER/ Golgi)
N-linked (on ER)
Glypiation
C-linked
Phosphoglycosylation
Types of acetylation
N-terminal
Lysine
N-terminal acetylation
Co-trans in euk
Synthesis
localisation
Stability
Lysine acetylation
Txn factor linked
For gene expression / activation
L lysine >< acetyl-lysine
N-terminal acetyltransferases
Transfer from Ac-CoA to alpha amino group of 1st amino acid res
Specific to N-termini
Irreversible
Antagonistic acetylation
Acetylation removes + charge > wraps less tightly around histone > ^effector protein binding / txn ^ >txn hyperactivity
Histone DAC/ AT location
cytoplasm
nucleus
altered biological effects in malignant cells
decreased proliferation/ migration
increased cell cycle/ cell death
methylation no. transfers on to lysine
1/2/3m
methylation no. transfers on to arginine
1/2
what donates methyl in methylation
S-adenosylmethionine
carbonyl methylation
generally reversible
modulates reaction
N-methylation
irreversible
onto new amino acids
arginine methylation functions
RNA processing
gene txn
DNA damage repair
protein translocation
signal transduction
lysine methylation
histone function regulation
epigenetic regulation of transcription
KMT
lysine methyl transferase
P53
Tumor suppressor
targets expression of downstream target gene regulation
lys/ arg rich
what is P53 regulated by
PMT/ acetylation/ phosphorylation/ methylation in N/C terminals
