golgi complex and membrane trafficking Flashcards
why do we need a secretory pathway
cells must be able to identify proteins and make sure theyre transferred to the correct location
which proteins do not use secretory pathway
ones going to mitochondria and chloroplasts
what is the sequence of events in secretory pathway
ER to Golgi then packaged into vesicles and sent to extracellular location
describe the maintenance behind secretory pathway
can go in opposite direction
endosymbiosis into ER
return proteins back to earlier stages
what is ER export
movement of subsatnces from ER to golgi
describe the process of ER export
in ER:
- proteins folded and packaged into vessicles
(soluble proteins in lumen and transmembrane in membrane of vesicles)
vesicles budded off contain COPII coats
co protein coordinates forward movement to secretory pathway
forms vestibular tubular cluster at golgi complex
what are the two specific ER exit signals
di acidic amino acids
di hydrophopbic
describe di acidic amino acids signsl
on cystolic side
glu or asp
targets transmembrane proteins to golgi complex
describe di hydrophobic signals
met
targets to transport to golgi complex
describe ER retrieval
recylcing system of KDEL sequences
vestibular tubular cluster recognises KDEL
KDEL binds to receptors creating a budding membrane with a COPI coat
describe the difference between COP1 and COPII
1 to ER
II to golgi
describe the structure of golgi complex
cis golgi network
three cisterna- cis medial, trans
trans golgi network
what is the golgi complex
processing factory of the cell
modifies proteins from ER
describe physiology of golgi complex
series of flattened stacks that have lumen and surrounding membrane - cisterna
what is the trans golgi network
distribution hub
proteins packaged into vesicles and sent out
where does n linked glycosylation occur
in ER
further modification in golgi complex
what is glycosylation
determines cellular destination
what are the enzymes for addition and removal of sugars in glycosylation
glycosyltransferases
glycosidases
what is o linked glycosylation
addition of sugar to serine/theranine residues
can only apply one sugar at a time
where is o linked glycosylation common
in cytoplasmic / nuclear proteins
what does o linked glycosylation do
acts as a signal to target correct location
what are an example of sugar molecules involved in o linked glycosylation
fructose
glucose
mannose
what are sphingomyelin and glycolipid made from
precursor cermide
what is ceramide composed ofq
sohingosine and fatty acid
what are 5 examples of golgi mediated PTM and where does it occur
sulfation of tyrosine residues-cis golgi phosphorylation- cis cisterna palmitoylation- medial cisterna proteolytic processing- trans cisterna oligomerisation- trans golgi
what is the cisternal maturation model
recyling of enzymes through migrating and maturing throughgolgi structure
what is the final job of the trans golgi network
targeting lysosome
what do lysosomal protein targeting require
modification of n linked glycosylation protein to mannose-6-phosphate which is specific target to move proteins to the lysosome
