Liu Protein Transport Flashcards
The GTPase _____ is found in the cytosol and nucleus and is required for protein import and export from the nucleus.
Ran.
T or F. Fully folded proteins can be transported in and out of the nucleus.
True.
In nuclear protein transport, Ran GAP is located in the _____ and Ran GEF is located in the ______.
GAP in cytosol
GEF in nucleus.
In protein nuclear import, what does GTP do? What does GTP binding do in nuclear export?
Nuclear import. GTP binds to nuclear import receptor, releases cargo.
Nuclear export. GTP binds to export receptor with cargo, brings it to cytosol.
T or F. Protein translocation into the mitochondria is co translational.
False. protein must be fully translated.
T or F. Fully folded proteins can be translocated into the mitochondria.
False. proteins are fully translated but must be unfolded.
What are the names of the translocation receptors mitochondria have to bring in proteins from the cytosol?
TOM and TIM (outer and inner)
Where on the protein is the signal sequence if a protein is destined for a peroxisome?
C terminal.
Are proteins transported to peroxisomes unfolded or fully folded?
Fully folded.
Assign “unfolded” or “fully folded” to the proteins translocated into the
1) nucleus
2) mitochondria
3) peroxisome
1) folded
2) unfolded
3) folded
What is the name of the protein that recognizes ER signal sequences and brings the mRNA to the ER?
SRP Signal Recognition Protein.
Is polyribosomal translation possible in mRNA translated on the surface of ER?
Yes.
What is SEC 61?
ER protein translocator.
A protein has an N terminal signal sequence, and a stop transfer sequence in the middle. Where is the N terminal, C terminal? (Cytosol, lumen of ER)
N terminal in lumen of ER,
C terminal in cytosol
Imagine a protein with a signal sequence in the middle of the protein. Where is the N terminus and C terminus?
Tricky. It can be either orientation. N term in lumen, C in cytosol. or C in lumen, N in cytosol. Depends on which side of the SEC 61 translocator protein the signal binds to.
Imagine a protein with a signal seqence mid protein, and a stop transport signal after (nearer C terminal). Where is the N terminus and C terminus?
Both N terminus and C terminus cytosolic.
In complex multipass proteins, where is the N terminus (lumen or cytosol)?
lumen. a second start transfer sequence will bring the protein into the cytosol.
What is Parkin?
An E3 ubiquitin ligase used in ERAD ER associated degradation.
What are some diseases involving faulty protein degradation?
Cystin Fibrosis, Parkinsons
What is Cystic Fibrosis?
Deletion of Phe at position 508 of Cystic Fibrosis Transmembrane conductance Receptor (CFTR). All proteins degraded by ERAD. No chloride regulation.
What are the 3 major types of glycoproteins?
N linked (asparagine, GlcNac) O linked (serine, threonine, GalNac, HyL) GPI anchored (glycosylphosphatidylinositol links PM to protein).
N linked glycoproteins can be further categorized to complex, hybrid and high mannose. They all share 2 ____ at the base and 2 ____ which serve as the two branches.
Glcnac bases, Mannose branches.
______ inhibits the first step of N linked glycosylation (dolichol pp oligosaccharide giving oligosaccharide to Asn)
Tunamycin.
How are high mannose and complex N linked glycosylation made? Start with glcnac glcnac manose manose manose glucose glucose.
Glucosidases and a little mannosidase used to make high mannose oligosaccharides.
Glcnac is added to prevent endopeptidases, gal is added and other random shit. makes complex oligosaccharides.
