protein targeting and export 4

Question 1

structure of translocon

Answer 1

3 sec 61 protein subunits A, B, Y
signal alpha forms a plug at the base of the structure
able to hinge allowing proteins to pass through

Question 2

TM domain have alpha helices containing

Answer 2

hydrophobic AA

Question 3

regions outside the membrane tend to be

Answer 3

hydrophobic

Question 4

how are the proteins classified

Answer 4

orientation and number of TM domains

Question 5

importance of glycosylation

Answer 5

almost all soluble and membrane bound proteins are N-glycosylated as they emerge from ER membrane translocon pore
can also be O-glycosylated after they have been completely synthesised

Question 6

glycosylation

what does it do

Answer 6

targets proteins to specific locations or

labels for secretion

Question 7

glycosylation

what does it stop

Answer 7

incorrect folding of protein

Question 8

glycosylation

what does it protect

Answer 8

against proteolytic degradation

Question 9

glycosylation

what else does it do

Answer 9

assists in stabilisation
stabilises or locks protein topology within membrane
confers specific recognition properties inside and outside cell

Question 10

proteins are rapidly glycosylated on ASN residues after what

Answer 10

passing through the pore

Question 11

step 1 in rapid glycosylation

Answer 11

14-mer is transferred while the protein is still being translated

Question 12

step 2-4 in rapid glycosylation

Answer 12

14-mer is further processed by glycosidase enzymes to remove the glucose residues and one of the mannose
1 glucose may be added later to help folding