peroxisomes Flashcards
what is the main function of peroxisomes?
beta fatty acid oxidation
what happens in zellweger syndrome?
lack of or low no of peroxisomes, enzymes mislocalised to the cytosol instead of peroxisomes
how many different complementation groups?
14
which group has milder symtoms
A
class 1 biogenesis mutants
affect matrix protein import
class 2 biogenesis mutants
affects membrane biogenesis so no peroxisomes
class3 biogenesis mutants
shape no. and distribution effected, miler symptoms
what is PTS1
peroxisome targetting sequence, on c ter of peroxisome enzymes
what two proteins form a pore in the membrane for peroxisome enzyme import?
pex5 and 14
what complex is responsible for the extraction of ubiquitinated pex5 from the membrane?
pex15,1,6 ATPase complex
steps of pulse chase experiment
GFP-PTS1 marker just after GAL1 promoter. switch on GAL promoter by growing on galactose for 3 hours then chase on glucose for 2 hours
how do peroxisomes form?
by fission or can form de novo in mutants
where are pex3 restricted to in pex19 deletion mutants
ER
assay for de novo peroxisome formation
constitutively express HcRed-PTS1 marker, induce GAL-GFP-PTS1 by pulsing on galactose for 3hours. then stop expression and chase. red peroxisomes de novo. oranage are formed from new and preexisting peroxisomes
what are dmn1 and vps1 required for?
normal peroxisome number
what other proteins are required for peroxisome fission?
fis1, caf4, mdv1, dmn1
mating assay for fission
label vps1/dmn1 double knockouts with GFP-PTS1, galactose pulse for 3 hours, chase on glucose 2 hours, mate with pex3 deletions to recover cells. vps1 recovers the cells
what organelle provides peroxisomes with essential membrane consituients?
ER
what mechanisms need to be switched on for peroxisome proliferation?
beta-oxidation enzymes and genes required for peroxisome biogenesis- ORE
what does olate activate?
oaf1p
what does oaf1p bind to
pip2p
what does binding of hetrodimer to oelate response element do?
causes peroxisome biogenesis and postive feedback to activate more pip2
what is required for peroxisome transport to bud?
actin cytoskeleton and myo2 and inp2
what does inp1 do
anchors peroxisomes to periphery of mother cell and captures newly arrived peroxisomes in the bud
