review 239 actual exam questions and
answers (new update) McMaster
University
,is the RER dynamic or stationary? - --dynamic
what is the function of the RER? - --co-translational transport, protein modification, formation of vesicles
that will transport proteins from ER to Golgi
what is the function of the SER? - --fatty acid and phospholipid synthesis, carbohydrate metabolism,
regulate Ca2+ conc in the cytosol
what are the post translational modifications in the ER? - --- glycosylation
- protein folding
- disulphide bond formation
- proteolytic cleavage
do modifications to proteins embedded in the ER membrane occur in the luminal portion or the
transmembrane domain or the cytosolic portion? - --luminal
this protein modification is important for proteins that mediate cell interactions with the extracellular
matrix and for receptor-ligand recognition - --glycosylation
this protein modification is common on proteins that are secreted from the cell and proteins embedded
in the cell membrane - --glycosylation
what is the most common form of glycosylation? - --N-linked
N-linked glycosylation adds a polysaccharide to which group of which amino acid? - --NH2 group of the
R-group of asparagine
, these proteins recognize modified proteins and assist in protein folding in a similar way as chaperones -
--lectins
what are the two types of lectins? - --calnexin and calreticulin
where is calnexin found? - --ER membrane
what is BiP? mention 3 functions - --- ER-resident HSP70 chaperone
- transfers proteins from ER through the translocon by binding to proteins as soon as they appear on the
luminal side of the membrane during co-translational transport
- initiate unfolded protein response in the ER
what are the co-chaperones of BiP? - --Hsp40 and NEF
is cytoplasm a reducing or an oxidizing environment? - --reducing
is ER a reducing or an oxidizing environment? - --oxidizing
does disulphide bond formation occur in reducing or oxidizing environment? - --oxidizing
this protein is one of many proteins secreted into the intestine where it aids in the digestion of RNA by
cleaving it into small pieces - --RNAse A
what is the protein that resides in the ER that promotes oxidation? - --protein disulphide isomerase (PDI)
does proteolytic cleavage in the ER happen in the lumen or the cytosol? - --lumen