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Questions and Answers
What is the purpose of treating cells with [35S]methionine for 0.5h?
What is the purpose of treating cells with [35S]methionine for 0.5h?
- To label all newly synthesized proteins (correct)
- To study cellular respiration
- To remove all proteins from the cell
- To induce mutations in proteins
How are proteins visualized after being fractionated from the ER, Golgi, and membrane?
How are proteins visualized after being fractionated from the ER, Golgi, and membrane?
- By conducting PCR
- Using autoradiography (correct)
- By using electron microscopy
- Through western blotting
In the context of protein sorting and secretion, what is the role of membrane-bound vesicles?
In the context of protein sorting and secretion, what is the role of membrane-bound vesicles?
- Acting as energy storage sites in the cell
- Transporting protein cargo into, out-of, and within the cell (correct)
- Serving as protective barriers around the nucleus
- Anchoring proteins to the cell membrane
What is responsible for sending out proteins to the correct place inside or outside the cell?
What is responsible for sending out proteins to the correct place inside or outside the cell?
Which organelle is involved in sorting proteins to the plasma membrane or to lysozymes?
Which organelle is involved in sorting proteins to the plasma membrane or to lysozymes?
What is the purpose of the N-terminal signal sequence in proteins?
What is the purpose of the N-terminal signal sequence in proteins?
Which step involves opening of the translocon to allow insertion of the signal sequence and the growing peptide chain?
Which step involves opening of the translocon to allow insertion of the signal sequence and the growing peptide chain?
Where are carbohydrate chains added to proteins in glycosylation of proteins?
Where are carbohydrate chains added to proteins in glycosylation of proteins?
Which type of glycosylation involves adding 1 - 4 carbohydrate residues?
Which type of glycosylation involves adding 1 - 4 carbohydrate residues?
What is the function of protein disulfide isomerase (PDI) in the ER?
What is the function of protein disulfide isomerase (PDI) in the ER?
Which enzyme is responsible for adding the first sugar to Dolicol phosphate in N-linked glycan biosynthesis?
Which enzyme is responsible for adding the first sugar to Dolicol phosphate in N-linked glycan biosynthesis?
What triggers the unfolded protein response in the ER?
What triggers the unfolded protein response in the ER?
What is the role of Ire1 in the unfolded protein response?
What is the role of Ire1 in the unfolded protein response?
Which structure is transferred to an Asp residue in the ER lumen during N-linked core glycan biosynthesis?
Which structure is transferred to an Asp residue in the ER lumen during N-linked core glycan biosynthesis?
What assists proteins in folding into their native conformation in the ER lumen?
What assists proteins in folding into their native conformation in the ER lumen?
Which lipid is involved in the addition of sugars during N-linked core glycan biosynthesis?
Which lipid is involved in the addition of sugars during N-linked core glycan biosynthesis?
What happens when a protein receives a 'stop transfer' signal during insertion into the ER membrane?
What happens when a protein receives a 'stop transfer' signal during insertion into the ER membrane?
In the secretory pathway, where do proteins destined for lysosomes go?
In the secretory pathway, where do proteins destined for lysosomes go?
How are proteins moved from the golgi apparatus back to the ER during the secretory pathway?
How are proteins moved from the golgi apparatus back to the ER during the secretory pathway?
Where are proteins that are destined for regulated secretion sent by the trans-golgi network (TGN)?
Where are proteins that are destined for regulated secretion sent by the trans-golgi network (TGN)?
Which vesicles are responsible for transporting golgi resident proteins back to an earlier portion of the golgi?
Which vesicles are responsible for transporting golgi resident proteins back to an earlier portion of the golgi?
What is the main function of the golgi complex in the secretory pathway?
What is the main function of the golgi complex in the secretory pathway?
Which structure is responsible for directing ribosomes with N-terminal signal sequences to the endoplasmic reticulum?
Which structure is responsible for directing ribosomes with N-terminal signal sequences to the endoplasmic reticulum?
In the co-translational translocation of proteins, what is required for SRP to target the ribosome to the ER membrane?
In the co-translational translocation of proteins, what is required for SRP to target the ribosome to the ER membrane?
Which step in protein secretion involves the insertion of the signal sequence and the growing peptide chain into the translocon?
Which step in protein secretion involves the insertion of the signal sequence and the growing peptide chain into the translocon?
What is the specific function of the N-terminal signal sequence in proteins that need to be sorted within the cell?
What is the specific function of the N-terminal signal sequence in proteins that need to be sorted within the cell?
What is the unifying principle of both the secretory and endocytic pathways?
What is the unifying principle of both the secretory and endocytic pathways?
In vesicle docking, what proteins are responsible for the fusion of a vesicle with its target membrane?
In vesicle docking, what proteins are responsible for the fusion of a vesicle with its target membrane?
Which type of vesicle is responsible for transporting proteins from the rough ER to the Golgi?
Which type of vesicle is responsible for transporting proteins from the rough ER to the Golgi?
What initiates vesicle budding in the process of vesicle formation?
What initiates vesicle budding in the process of vesicle formation?
Which proteins ensure that a vesicle fuses with the correct target membrane during vesicle docking?
Which proteins ensure that a vesicle fuses with the correct target membrane during vesicle docking?
Which technique is used to label all newly synthesized proteins in cells?
Which technique is used to label all newly synthesized proteins in cells?
In the context of studying genetic secretory mutants, what can one investigate using genetic engineering and mutagenesis?
In the context of studying genetic secretory mutants, what can one investigate using genetic engineering and mutagenesis?
What is the main purpose of treating cells with non-isotopic methionine after labeling with [35S]methionine?
What is the main purpose of treating cells with non-isotopic methionine after labeling with [35S]methionine?
Which organelles are proteins fractionated from after being labeled with [35S]methionine?
Which organelles are proteins fractionated from after being labeled with [35S]methionine?
What is the significance of using membrane-bound vesicles in protein transport within the cell?
What is the significance of using membrane-bound vesicles in protein transport within the cell?
What is the main function of the rough ER in protein sorting and secretion?
What is the main function of the rough ER in protein sorting and secretion?
In the context of the secretory pathway, what is the significance of transport vesicles?
In the context of the secretory pathway, what is the significance of transport vesicles?
How are non-secreted cytosolic proteins distinguished from secretory proteins in terms of their generation?
How are non-secreted cytosolic proteins distinguished from secretory proteins in terms of their generation?
What is the fate of secretory proteins after passing through the Golgi complex?
What is the fate of secretory proteins after passing through the Golgi complex?
In protein sorting, what would be the consequence if a protein lacks an ER signal sequence?
In protein sorting, what would be the consequence if a protein lacks an ER signal sequence?
What is the role of Sar1 in vesicle formation during the secretory pathway?
What is the role of Sar1 in vesicle formation during the secretory pathway?
Which protein is responsible for the stable docking and membrane fusion of vesicles in the secretory pathway?
Which protein is responsible for the stable docking and membrane fusion of vesicles in the secretory pathway?
How do ER luminal proteins get retrieved from the golgi back to the ER in the secretory pathway?
How do ER luminal proteins get retrieved from the golgi back to the ER in the secretory pathway?
Which protein is involved in dissociating the SNARE complex during membrane fusion in the secretory pathway?
Which protein is involved in dissociating the SNARE complex during membrane fusion in the secretory pathway?
What is the function of the KDEL receptor in protein trafficking?
What is the function of the KDEL receptor in protein trafficking?
What is the role of Ero1 in the ER lumen?
What is the role of Ero1 in the ER lumen?
Which protein is responsible for catalyzing Cys-Cys bond formation in secretory or membrane-bound proteins?
Which protein is responsible for catalyzing Cys-Cys bond formation in secretory or membrane-bound proteins?
In the context of glycosylation of proteins, which amino acid residue is involved in O-linked carbohydrate chain addition?
In the context of glycosylation of proteins, which amino acid residue is involved in O-linked carbohydrate chain addition?
What is the primary function of Ire1 in protein quality control in the ER?
What is the primary function of Ire1 in protein quality control in the ER?
What is the significance of Dolicol phosphate (DP) in N-linked core glycan biosynthesis?
What is the significance of Dolicol phosphate (DP) in N-linked core glycan biosynthesis?
Which process is visualized by fluorescence microscopy using GFP-tagged proteins?
Which process is visualized by fluorescence microscopy using GFP-tagged proteins?
What is the primary function of chaperones in the ER lumen?
What is the primary function of chaperones in the ER lumen?
In N-linked glycan biosynthesis, what is the role of the 7 residue intermediate that is 'flipped' across the ER membrane?
In N-linked glycan biosynthesis, what is the role of the 7 residue intermediate that is 'flipped' across the ER membrane?
Study Notes
Protein Synthesis and Sorting
- Treating cells with [35S]methionine for 0.5h labels all newly synthesized proteins.
- The purpose of this treatment is to visualize proteins after fractionation from the ER, Golgi, and membrane.
Protein Trafficking and Secretion
- Membrane-bound vesicles play a crucial role in protein sorting and secretion.
- They are responsible for sending proteins to the correct place inside or outside the cell.
- The Golgi apparatus is involved in sorting proteins to the plasma membrane or to lysosomes.
- The N-terminal signal sequence is responsible for directing proteins to the correct location.
Protein Modification and Folding
- The N-terminal signal sequence is inserted into the translocon during protein synthesis.
- Carbohydrate chains are added to proteins in the Golgi apparatus during glycosylation.
- O-linked glycosylation involves adding 1-4 carbohydrate residues.
- Protein disulfide isomerase (PDI) helps proteins fold into their native conformation in the ER lumen.
ER Quality Control
- The unfolded protein response (UPR) is triggered by the accumulation of unfolded proteins in the ER.
- Ire1 plays a key role in the UPR, helping to maintain ER homeostasis.
- Protein disulfide isomerase (PDI) also helps to correct protein folding in the ER.
Vesicle Formation and Transport
- Vesicle budding is initiated by the formation of a bud on the ER membrane.
- Sar1 is involved in vesicle formation during the secretory pathway.
- SNARE proteins are responsible for the fusion of vesicles with their target membrane.
- Rab proteins ensure that vesicles fuse with the correct target membrane.
Golgi Apparatus and Protein Secretion
- The Golgi apparatus is responsible for sorting and modifying proteins for secretion.
- Proteins destined for regulated secretion are sent to the trans-Golgi network (TGN).
- Vesicles that transport proteins from the rough ER to the Golgi are called COPII vesicles.
- The main function of the Golgi apparatus is to modify and sort proteins for secretion.
Protein Quality Control and Retrieval
- The KDEL receptor is involved in protein retrieval from the Golgi back to the ER.
- Ero1 is responsible for catalyzing Cys-Cys bond formation in secretory or membrane-bound proteins.
- Chaperones in the ER lumen help proteins fold into their native conformation.
- The 7-residue intermediate is involved in N-linked core glycan biosynthesis.
Visualization and Analysis
- Fluorescence microscopy using GFP-tagged proteins can visualize protein trafficking and secretion.
- Genetic engineering and mutagenesis can be used to investigate protein secretion and sorting in genetic secretory mutants.
- Treating cells with non-isotopic methionine after labeling with [35S]methionine can be used to analyze protein synthesis and secretion.
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Description
Test your knowledge on protein post-translational modifications such as glycosylation and covalent stabilization through Cys-Cys bond formation. Learn about the assembly of multi-subunit conformations and cleavage into active forms. Understand the different types of glycosylation involving serine, threonine, and asparagine residues.
