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Posttranslational Modifications
Plaas
16
Biochemistry
Professional
10/13/2011

Additional Biochemistry Flashcards

 


 

Cards

Term

 

 

 

SPP intramembrane aspartyl protease

Definition

 

memb-bound proteins or proteins destined for secretion are synth'd by ribosomes assoc w ER memb, contain signal peptide at N-Terminus, which binds with SRP (signal recocnition particle), which allows it to bind translocon in ER membrane

 

SPP cleaves SRP

Term

 

 

pre-proteins vs pro-proteins

Definition

 

 

 

pre-proteins still have signal peptide at N-terminus

 

in pro-proteins, signal peptide has been cleaved by SPP

Term

 

 

 

 

N-linked glycosylation

Definition

 

important in some EU protein folding

 

oligosaccharides (high-mannose oligos or complex oligos) are added to protein

 

further phosphorylation in Golgi of 1+ mannose residues

Term

 

 

 

CDGs (congenital disorders of glycosylation)

Definition

 

lack ability to phosphorylate mannose residues-->

mutations in glycosylide oligosaccharide structures

 

multisystemic disorders w neurologic involvement

 

tx: enzyme replacement therapy

Term

 

 

 

 

acetylation and methylation of aa

Definition

 

Lysine residues in histones

 

regulates gene transcription

 

acetyl=ON

methyl=OFF

Term

 

 

 

aas often targeted for phosphorylation regulation

Definition

 

 

serine

threonine

tyrosine

Term

 

 

 

 

Tyrosine sulfation

Definition

 

 

regulates protein structure

 

universal sulfate donor=PAPS

 

sulfation is NOT reversible

Term

 

 

 

proteolytic processing for activity

Definition

 

 

proteins are activated after translation by modification

 

 

can be extracellular or intracellular

Term

 

 

proinsulin

Definition

 

 

synthesized in ER of pancreatic Islet cells

Term

 

 

 

 

proinsulin processing

Definition

 

 

moved from ER to Golgi, packaged into secretory vesicles, then processed by proteases-->mature insulin

Term

 

 

 

N- and C-peptidases and proteolytic processing

Definition

 

 

modify procollagen extracellularly --> tropocollagen-->assemble into collagen fibrils

Term

 

 

 

 

proteasome

Definition

 

 

protein complex with active sites for protein degradation inside

 

loc in cytosol and nucleus

Term

 

 

 

 

Ubiquitin

Definition

 

a small protein tag that marks proteins for degradation

 

1. ubiquitin-activating enzyme binds ubiquitin to enz via ATP bond

2. uniquitin-conjugating enz transfer ubiq to substrate protein

3. ubiquitin-protein ligases-->covalent attachment of ubiquitin to internal Lys

4. degradation of protein, recycling of ubiquitin

Term

 

 

 

 

defective ubiquitination-->

Definition

 

cancer, neurodegenerative diseases

Term

 

 

SUMO-ylation

Definition

 

posttranslational modification

 

sim to ubiquitination, but NOT used to tag proteins for degradation

 

may provide docking/binding sites for protein-protein interactions

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