protein trafficking

Question 1

what is the KDEL sequence

Answer 1

lysine-aspartic acid-glutamic acid-leucine

Question 2

what is the purpose of the KDEL sequence?

Answer 2

marks ER-resident enzymes so they are transported from the Golgi back to the ER
kdel receptor on Golgi recognises KDEL sequence

Question 3

N-linked glycosylation

Answer 3

sugar attached to nitrogen in asparagine

forms N-acetylglucosamine

Question 4

O-linked glycosylation

Answer 4

sugar attached to oxygen in threonine

forms N-acetylgalactosamine

Question 5

what is the quality control signal?

Answer 5

2 N-acetylglucosamine residues
many mannose residues
3 glucose residues

Question 6

which residues does the initial addition of carbohydrates occur via?

Answer 6

asparadine

Question 7

describe step by step process of protein glycosylation

Answer 7

1. n-linked glycosylation in rough ER
2. glucose residues removed in cis golgi
3. mannose residues trimmed back
4. attachment of N-acetylglucosamine on both sides
5. addition of sialic acid/NANA
6. sulphation of tyrosines and carbohydrates in trans golgi

Question 8

type 1 diabetes

Answer 8

high blood glucose
misfolded proinsulin due to mutation
protease in secretory vesicle unable to cleave c-peptide off proinsulin
dysfunctional pro-insulin cannot bind to insulin receptors
antibodies generated against pancreatic cells - destruction of pancreatic cells

Question 9

what is opiomelanocortin cleaved into in pancreas

Answer 9

ACTH

β-lipotropin

Question 10

what is opiomelanocortin cleaved into in neuron?

Answer 10

⍺-MSH
β=MSH
γ-lipotropin
β-endorphin