L5 - PTM Flashcards
What is PTM?
addition of a chemical group or molecule to specific amino acids of a protein
What do PTMs do?
provide a means to control protein activity, function, stability, interactions or localisation
What do we use to add/remove groups to proteins?
enzymes
PTMs can
- create/block binding sites
- change confirmation of a protein
- affect the stability of a protein
- rapid signal amplificatio
- allow cross-talk
How many protein kinases are there?
538
What molecule is phosphate added from?
ATP
What group of phosphate from ATP is it added from?
gamma
What residues are phosphates added to?
Threonine, tyrosine, serine.
What does protein phosphorylation mediate?
cell signalling
What are the advantages of using phosphorylation & de-P as a control mechanism?
rapid, easily reversible and does not need new proteins to be made/degraded
What sort of charge does phosphorylation add?
Negative
What sort of mechanism occurs in phosphorylation?
Nucleophilic attack
What occurs in the nucleophilic attack in phosphorylation?
- kinase attacks H in OH group in serine, negative O attacks PO3 in ATP = phosphoserine & ADP
What happens in lysine acetylation - charge wise?
Addition of acetyl = neutralising lysine positive charge
What happens if lysine is acetylated?
creates a binding site for specific proteins that recognised acetlylated lysine
What sort of mechanism occurs in lysine acetylation?
Nucleophilic attack
What occurs in the nucleophilic attack in lysine acetylation?
aceytlase attacks the H in NH3, and then N attacks the carbonyl C in acetyl-CoA, then the CoA is removed
How do we make lysine more reactive, activating it for a direct nucleophilic attack on acetyl-CoA
glutmate residue in enzyme activates a H2O molecule, removing a protin from the lysine amine group. deproton = more reactive
What was lysie modification initially characterised as?
histone modifications controlling chromatin structure
What proteins does lysine acetylation affect?
CdK9, FEN1, NBS1, PCNA, RB.
Does lysine methylation neutralise the positive charge pf lysine?
No.
What are the different types of meythlation?
mono, di, tri
What acts as a cofactor and methul donor for lysine (and argenine) methylation
SAM. - S-Adenosyl methanionine.
What type of PRMT results in asymmetric di-methyl-argenine?
PRMT 1
What type of PRMT results in asymmetric di-methyl-argenine?
PRMT 2
What do writer proteins do?
write the signature on proteins
What do eraser proteins do?
erase the signature on proteins
What do reader proteins do?
read the signature on proteins
What form of chromatin activates transcription?
relaxed
Histone 3k4 is responsible for….
activation!
histone 3k9?
acylate = activate, methylate = silence
histoke 3k27
SHUT IT DOOOOWN
histone 3k36
other biological processes?
histoke 4ks?
forms a tetramer with H3 - acylated and methylated
N terminal
histone 4k12
acetylated NOT methylated
Facilitates transcriptional elongation
Histone 4k16
acetylated not mythlated - txn activation and repressio
h4k20
methylated.
Lysine ubiquitination
adding ubiquitin
how many amino acids does ubiquitin have
76
how many steps in ubiquitination
3 steps
what happens during ubiquitination
step1: ubiquitin activating enzyme E1
step2: ubiquitin conjugating enzyme E2
step3: ubiquitin ligase E3
How many E1 in humans
2
how many E2?
35
how mny E3
617
Different types of ubiquitin chains have _____ cellular roles
different
what is the function of M1 chain?
signalling and anti-bacterial autophagy
What is the function of K63 chain
antibacterial autophage,
DNA damage,
Signalling
