Protein Trafficking Flashcards
What is protein trafficking?
A: Protein trafficking is the process by which proteins are synthesized, folded, modified, and transported to their final destinations within or outside the cell.
What are the key organelles involved in protein trafficking?
A: The rough endoplasmic reticulum (RER), Golgi apparatus, vesicles, and lysosomes.
What is the role of molecular chaperones in protein folding?
A: Chaperones assist in the correct folding of nascent polypeptides, preventing aggregation and misfolding.
How are proteins targeted for specific cellular locations?
A: Proteins contain signal sequences that direct them to their appropriate organelles, such as the ER, mitochondria, or nucleus.
What is the difference between co-translational and post-translational protein targeting?
A: Co-translational targeting occurs during protein synthesis, while post-translational targeting occurs after translation is complete.
The secretory pathway transports proteins from the
ER to the Golgi and then to their final destinations.
N-linked glycosylation occurs in the ER, while O-linked glycosylation occurs in the
Golgi.
Proteins destined for the ER contain a
KDEL retrieval sequence.
The ubiquitin-proteasome system (UPS) degrades
misfolded or damaged proteins.
The lysosome is responsible for
autophagy and recycling cellular components.
All proteins are synthesized in the rough ER.
False – Some proteins are synthesized in the cytoplasm and targeted to specific organelles post-translationally.
The Golgi apparatus is involved in modifying and sorting proteins.
True.
The signal sequence for ER targeting is cleaved after the protein enters the ER lumen.
True.
Ubiquitination marks proteins for secretion outside the cell.
False – Ubiquitination marks proteins for degradation by the proteasome.
The ER-resident chaperone that facilitates protein folding is called __________.
A: BiP.
Proteins targeted for degradation via the UPS are tagged with __________.
A: Ubiquitin.
The __________ pathway involves vesicular transport from the ER to the Golgi and beyond.
A: Secretory.
The proteasome degrades proteins via an ATP-dependent process called __________.
A: Proteolysis.
What is the role of the translocon in co-translational translocation?
A) Degrades misfolded proteins
B) Facilitates protein entry into the ER
C) Modifies proteins with sugar residues
D) Recycles vesicles in the Golgi
A: B) Facilitates protein entry into the ER.
Which post-translational modification targets proteins to the plasma membrane?
A) Glycosylation
B) Phosphorylation
C) Prenylation
D) Ubiquitination
A: C) Prenylation.
What sequence allows proteins to be retained in the ER?
A) NLS
B) KDEL
C) PTS1
D) SRP
A: B) KDEL.
Which cellular system is responsible for bulk degradation of proteins and organelles?
A) Proteasome
B) Lysosome
C) Peroxisome
D) Endosome
A: B) Lysosome.
A patient with cystic fibrosis has defective CFTR protein trafficking. What cellular process is disrupted?
A: ER-to-Golgi transport and membrane insertion.
A researcher inhibits the ubiquitin-proteasome system in cells. What is the likely consequence?
A: Accumulation of misfolded and damaged proteins.
