Endoplasmic Reticulum Flashcards
What mutation causes cystic fibrosis?
Deletion of F508 for ATP binding in cftr channel causes protein to enter ERAD
Mutations in collagen causes what disease?
Osteogenesis imperfecta
Which genes are implicated in osteogenesis imperfecta?
COL1A1 and 2
Alpha-1-antitrypsin deficiency causes what symptoms?
Emphysema
Alpha-1-antitrypsin is what type of molecule?
A protease inhibitor that acts in the lungs
What sequence is involved in retrieval of cholera toxin?
KDEL sequence on A subunit for endocytosis to cis Golgi to ER
How does the cholera toxin enter the cell?
Binds to GMI glycolipid by B subunit
What cellular effects does cholera have?
A1 unit activates cAMP the PKA for CFTR to export Cl-. Osmosis out causes diarrhoea symptoms
Does ricin toxin have a retrieval sequence?
No!
How does ricin enter a cell?
B unit uses beta-1,4-galactose residues to bind to glycolipid and glycoproteins
What enzymatic activity does the A unit of ricin have?
Unfolded in ER then released into cytoplasm. Depurinates A4324 on 28S rRNA so elongation factors can bind
How does HCMV exploit ERAD?
Integral membrane proteins US2 and 11 target MHC1 (produced in ER) heavy chain to ERAD so no presentation of antigens for immune action
What action does E3-19K have in adenovirus?
Binds MHC1 luminal domain. KKXX motif used in retrieval for ERAD
What PTM occurs in the ER?
Oxidation to form disulphide bonds
addition on N-oligosaccharides
Folding using Calnexin and ERp57 chaperones
What is the ERAD pathway?
Improper folding causes glucose to be added by glucosyl transferase
Removal of mannose sugars
reterotranslocation
polyubiquitination and degradation
