p.19
GTPases in Vesicle Formation and Fusion
What is the role of GTPases?
They function in vesicle formation.
p.15
Clathrin-Mediated Endocytosis
What is the role of clathrin in cellular processes?
It is required for receptor-mediated endocytosis.
p.5
Unfolded Protein Response (UPR) Mechanisms
What are the main outcomes of the Unfolded Protein Response?
Restoration of normal ER function, degradation of misfolded proteins, and, if stress persists, apoptosis.
p.7
Unfolded Protein Response (UPR) Mechanisms
What triggers Ire1p oligomerization?
Accumulation of unfolded proteins in the ER.
p.13
Vesicular Trafficking Mechanisms
What does COPII transport?
From the ER to the Golgi.
p.17
Vesicular Trafficking Mechanisms
At which membranes do COPI and COPII function instead of clathrin?
Golgi and plasma membrane (PM).
p.24
Role of Rabs in Vesicular Docking Specificity
What variation exists in Rab GTPases?
Variation in Rab C-terminal tails.
p.20
GTPases in Vesicle Formation and Fusion
What happens when GTPase is activated?
Hydrophobic tail exposure occurs.
p.7
Unfolded Protein Response (UPR) Mechanisms
What happens to HAC1 u mRNA when Ire1p is activated?
It is spliced to form HAC1 i mRNA, which is then translated into Hac1p i.
p.21
SNARE Proteins and Membrane Fusion
What is the role of SNARE proteins in vesicular transport?
They guide vesicular transport by directing vesicles to the correct place.
p.22
SNARE Proteins and Membrane Fusion
What is a characteristic of at least one t-snare?
It is an integral-membrane protein.
p.3
Ubiquitylation and ER-Associated Degradation (ERAD)
Which complex is involved in the extraction of ubiquitylated misfolded proteins from the ER?
The Cdc48 Ufd1 Npl4 complex.
p.5
Unfolded Protein Response (UPR) Mechanisms
How does IRE1 contribute to the UPR?
It senses unfolded proteins and activates splicing of XBP1 mRNA, leading to the production of a transcription factor that enhances the expression of chaperones.
p.19
GTPases in Vesicle Formation and Fusion
What does GAP stand for?
GTPase Activating Protein.
p.17
Clathrin-Mediated Endocytosis
What role does adaptin play in vesicle formation?
Adaptin binds clathrin and receptors, acting as a bridge.
p.17
Vesicular Trafficking Mechanisms
Can vesicles be tubular?
Yes, vesicles can be tubular.
p.3
Ubiquitylation and ER-Associated Degradation (ERAD)
What does ubiquitylation trigger in the context of misfolded proteins?
It triggers their retro translocation to the cytosol.
p.5
Unfolded Protein Response (UPR) Mechanisms
What role does PERK play in the UPR?
It phosphorylates eIF2α, reducing general protein synthesis and allowing selective translation of stress response proteins.
p.25
Function of SMAP Proteins in Vesicle Trafficking
What is the difference between SMAP1 and SMAP2 regarding their regulation?
SMAP2 appears to be a regulator of Arf1 in vivo, unlike SMAP1.
p.21
SNARE Proteins and Membrane Fusion
What do the letters 'V' and 't' represent in the context of SNAREs?
'V' stands for vesicle and 't' stands for target SNAREs.
p.15
Clathrin-Mediated Endocytosis
How many polypeptides make up one clathrin?
6 polypeptides (3 large and 3 small).
p.7
Unfolded Protein Response (UPR) Mechanisms
What is Ire1p?
A transmembrane serine-threonine kinase in the ER.
p.25
Function of SMAP Proteins in Vesicle Trafficking
With which protein does SMAP2 interact?
Clathrin heavy chain (CHC) and clathrin assembly protein CALM.
p.8
Vesicular Trafficking Mechanisms
What is the primary function of vesicular trafficking?
To allow proteins and vesicles to reach their destinations.
p.22
SNARE Proteins and Membrane Fusion
What is the effect of neural toxin proteases on neuronal snares?
They target and affect neuronal snares, as seen in botulism.
p.4
Unfolded Protein Response (UPR) Mechanisms
How does protein misfolding relate to Alzheimer's disease?
It leads to the formation of amyloid plaques and neurodegeneration.
p.3
Ubiquitylation and ER-Associated Degradation (ERAD)
What is the role of ubiquitylation in the ER-associated degradation (ERAD) process?
It is required for different steps of the ERAD process, facilitating the extraction of misfolded proteins from the ER membrane.
p.20
GTPases in Vesicle Formation and Fusion
What do GEFs determine in the vesicle budding process?
When the vesicle is ready to bud.
p.18
GTPases in Vesicle Formation and Fusion
What is the role of Dynamin in vesicle formation?
Dynamin forms a ring around the bud.
p.4
Unfolded Protein Response (UPR) Mechanisms
What role do prions play in disease?
They cause neurodegenerative diseases through misfolded proteins.
p.22
SNARE Proteins and Membrane Fusion
What is a coiled-coil structure in snares?
A tightly intertwined set of 4 α-helix domains.
p.24
Role of Rabs in Vesicular Docking Specificity
What role do Rab GTPases play in vesicular trafficking?
They ensure the specificity of vesicular docking.
p.7
Unfolded Protein Response (UPR) Mechanisms
What is the role of Hac1p i?
It is a transcriptional activator that upregulates UPR target genes.
p.2
Role of Calnexin and Calreticulin in Protein Folding
How do calnexin and calreticulin interact with glycoproteins?
They bind to the monoglucosylated oligosaccharide and hydrophobic segments of the unfolded glycoprotein in their ATP-bound state.
p.22
SNARE Proteins and Membrane Fusion
What are snares?
Integral-membrane proteins that pull membranes together.
p.17
Vesicular Trafficking Mechanisms
What prevents uncoating at membranes?
Specific mechanisms at the membranes prevent uncoating.
p.20
GTPases in Vesicle Formation and Fusion
What role do GTPases play in vesicle trafficking?
They are required for vesicle formation and fusion.
p.20
GTPases in Vesicle Formation and Fusion
What is the consequence of GTPase inactivation?
It falls off the membrane and triggers coat disassembly.
p.25
Function of SMAP Proteins in Vesicle Trafficking
What activity does SMAP2 exhibit?
GAP activity, similar to SMAP1.
p.23
SNARE Proteins and Membrane Fusion
What role do SNARE proteins play in cellular processes?
They promote membrane fusion.
p.13
Vesicular Trafficking Mechanisms
What are the two different processes involved in vesicle transport?
Vesicle budding and vesicle fusion.
p.22
SNARE Proteins and Membrane Fusion
How many α-helix domains are contributed by t-snares and v-snares?
Three by t-snares and one by v-snare.
p.24
Role of Rabs in Vesicular Docking Specificity
How do Rabs differ from coat assembly GTPases?
Rabs are different from coat assembly GTPases (ARFs).
p.25
Function of SMAP Proteins in Vesicle Trafficking
What does the SMAP gene family represent?
An important ArfGAP subfamily with common and distinct functions in vesicle trafficking.
p.11
Vesicular Trafficking Mechanisms
What is the primary function of vesicular trafficking?
To allow proteins and vesicles to reach their destinations.
p.10
Vesicular Trafficking Mechanisms
What is exocytosis?
The process by which vesicles transport substances out of a cell.
p.19
GTPases in Vesicle Formation and Fusion
What does GEF stand for?
Guanine Nucleotide Exchange Factor.
p.4
Unfolded Protein Response (UPR) Mechanisms
Which diseases are associated with protein misfolding?
Prion diseases and Alzheimer's disease.
p.21
SNARE Proteins and Membrane Fusion
How do vesicle-surface markers function in vesicular transport?
They direct vesicles to the correct location.
p.17
Vesicular Trafficking Mechanisms
Which proteins are involved in uncoating the vesicle?
Hsp70 chaperone and auxillin.
p.15
Clathrin-Mediated Endocytosis
What is a Triskeleion composed of?
3 large and 3 small polypeptides.
p.3
Ubiquitylation and ER-Associated Degradation (ERAD)
How does modification with ubiquitin chains assist misfolded proteins?
It guarantees guidance, recognition, and binding to the proteasome for efficient degradation.
p.5
Unfolded Protein Response (UPR) Mechanisms
What is the Unfolded Protein Response (UPR)?
A cellular stress response related to the endoplasmic reticulum (ER) that aims to restore normal function by halting protein translation and activating the signaling pathways that lead to increased production of molecular chaperones.
p.5
Unfolded Protein Response (UPR) Mechanisms
What happens if the UPR fails to resolve the stress?
It can lead to cell death through apoptosis.
p.7
Unfolded Protein Response (UPR) Mechanisms
What does Ire1p do to HAC1 mRNA?
Cuts it at two sites, removing a nonclassical intron.
p.25
Function of SMAP Proteins in Vesicle Trafficking
What is the role of SMAP1?
It is a GTPase-activating protein (GAP) for Arf6 that regulates clathrin-dependent endocytosis of transferrin receptors.
p.25
Function of SMAP Proteins in Vesicle Trafficking
What effect does overexpression of SMAP2 have?
It delays the accumulation of TGN38/46 molecule on the TGN.
p.25
Function of SMAP Proteins in Vesicle Trafficking
What pathway does SMAP2 function in?
The retrograde, early endosome-to-TGN pathway in a clathrin- and AP-1–dependent manner.
p.2
Role of Calnexin and Calreticulin in Protein Folding
What triggers the dissociation of glycoproteins from calnexin/calreticulin?
The action of glucosidase II removing the terminal glucose and a change in affinity of the polypeptide binding site.
p.5
Unfolded Protein Response (UPR) Mechanisms
What triggers the Unfolded Protein Response?
The accumulation of misfolded or unfolded proteins in the endoplasmic reticulum.
p.25
Function of SMAP Proteins in Vesicle Trafficking
Where does SMAP2 colocalize?
With adaptor proteins for clathrin AP-1 and EpsinR on early endosomes/trans-Golgi network (TGN).
p.7
Unfolded Protein Response (UPR) Mechanisms
What does Hac1p i bind to in order to activate gene expression?
The unfolded protein response element (UPRE) in gene promoters.
p.2
Role of Calnexin and Calreticulin in Protein Folding
What happens if folding does not occur rapidly after glycoprotein dissociation?
The glycoprotein is reglucosylated by UDP-glucose:glycoprotein glucosyltransferase.
p.2
Role of Calnexin and Calreticulin in Protein Folding
What happens to Asn residues in nascent polypeptide chains as they enter the ER?
They are glycosylated with an oligosaccharide of composition Glc3Man9GlcNAc2.
p.2
Role of Calnexin and Calreticulin in Protein Folding
What is the role of glucosidases I and II in the glycosylation process?
They rapidly remove the outermost two glucoses to reveal the monoglucosylated species.
p.2
Role of Calnexin and Calreticulin in Protein Folding
What is the function of the binding and release cycle of calnexin/calreticulin?
1) Prevents glycoprotein aggregation, 2) Retains non-native conformers for quality control, 3) Brings ERp57 into proximity for disulfide bond formation.
p.2
Role of Calnexin and Calreticulin in Protein Folding
What role does ERp57 play in the protein folding process?
It catalyzes disulfide bond formation and isomerization within the glycoprotein.
