Lecture 10: Protein sorting and transport II

Question 1

smooth er

Answer 1

contact sites with other organelles; lipid/cholesterol synthesis

Question 2

rough er

Answer 2

site of protein import and establishment of correct protein folding

Question 3

N-glycosylation

Answer 3

occur upon co-translational transport of a precursor protein at a consensus sequence of the protein

Question 4

Folding

Answer 4

ER chaperones help the protein fold

Question 5

topology

Answer 5

spatial location of the + charged amino acids determine the topology of ER transmembrane proteins

Question 6

Type I protein

Answer 6

If + charged amino acids follow the hydrophobic domain ( C terminus in the cytosol)

Question 7

Type II protein

Answer 7

If + charged amino acids precede in the hydrophobic domain ( N terminus in the cytosol)

Question 8

N linked glycosylation

Answer 8

initiated in ER, continued in golgi, required for protein quality control

Question 9

O linked glycosylation

Answer 9

occurs only in the golgi

Question 10

the er prevents

Answer 10

premature and incorrect folding of initial protein segments

Question 11

first line of defense for ER stress

Answer 11

unfolded protein response (UPR)

Question 12

ERAD

Answer 12

1. recognition of misfolded protein
2. export from ER
3. Deglycosylation
4. poly-ubiquitination
5. degradation

Question 13

ubiquitin is attached to

Answer 13

lysine residues on target protein

Question 14

poly-ubiquitination leads to

Answer 14

proteasome dependent degradation in cytosol

Question 15

if protein is folded properly

Answer 15

sorting into transport vesicles for golgi delivery