protein trafficking Flashcards
what is the KDEL sequence
lysine-aspartic acid-glutamic acid-leucine
what is the purpose of the KDEL sequence?
marks ER-resident enzymes so they are transported from the Golgi back to the ER
kdel receptor on Golgi recognises KDEL sequence
N-linked glycosylation
sugar attached to nitrogen in asparagine
forms N-acetylglucosamine
O-linked glycosylation
sugar attached to oxygen in threonine
forms N-acetylgalactosamine
what is the quality control signal?
2 N-acetylglucosamine residues
many mannose residues
3 glucose residues
which residues does the initial addition of carbohydrates occur via?
asparadine
describe step by step process of protein glycosylation
- n-linked glycosylation in rough ER
- glucose residues removed in cis golgi
- mannose residues trimmed back
- attachment of N-acetylglucosamine on both sides
- addition of sialic acid/NANA
- sulphation of tyrosines and carbohydrates in trans golgi
type 1 diabetes
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
what is opiomelanocortin cleaved into in pancreas
ACTH
β-lipotropin
what is opiomelanocortin cleaved into in neuron?
⍺-MSH
β=MSH
γ-lipotropin
β-endorphin