Protein Degradation and Protein Techniques Flashcards
Metabolic flexibility:
quick changes in concentrations of key regulatory enzymes, hormones, receptors, etc
Protine turnover
miss formed/folded - danger of forming bad protine aggregates - need to degrade them
made to be degraded and made over again
Numerous physiological processes are just as dependent on timely degradative reactions as they are on synthetic ones (ie cell cycle progression, synthesis and degradation of cyclin proteins)
Chaperones __
Proteasomes __
Birth
Death
Chaperones bind to __
exposed hydrophobic regions (should be on the inside if fully folded, if not shows that it is not fully folded, damaged, etc.)
Chaperones (many) are called
Many are called heat shock proteins (hsp): hsp60 and hsp70 family
Often many cycles of _____________required (energy requirement) to fold polypeptide correctly
ATP hydrolysis
hsp70
monomers
bind while being synthesized by binding to hydrophobic regions - ATP required
Chaperone functions
1 Assist - chaperone guides
2 Rescue - help refold that have miss folded
3 Protect - prevents exposed hydrophobic patches to start to aggregate - dangerous and toxic to cells
Hsp60
isolation chamber
Acts later, after a protein is fully synthesized
GroES cap (small chaperone)
symetrical - can bind to either side (not at same time)
in chamber so cant bind to other / issolated enviorment represents aqueous cell (can fold how it would in cell)
ATP - helps protine unfold and be encapuslated in chamber
another ATP binds, weakens cap
specific half life
protiens life span mesurement
All proteins turnover with a specific half-life depending on their function.
House-keeping proteins half life
structural - longer half life
House-keeping proteins typically have long half-lives (on the order of days)
Regulatory proteins half life
Regulatory proteins often have relatively short half-lives (on the order of min. to hrs.).
PEST rich sequences
high % of protines that have v half lives in cells
exibit short peptide sequence enriched in
Pro-Glu-Ser-Thr (indicator/red flag for degregation)
Degradative Signals:
flag protine to be degraded
1) PEST rich sequences
2) N terminous residues
3) hydrophobic patch on protines surrface
N terminous resudues
very basic or hydrophoic (bulky)
N-end rule