PCQ's a major player in the failing scene Flashcards
How many PCQ’s could you PCQ if PCQ’s PCQed PCQ’s?
2
Do proteosomes require ATP?
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do chaperones require ATP?
Yea Boiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
chaperones
- Expression increases upon unusually high temperatures
- Helps proteins fold
proteosomes
- degrades proteins
- once proteins are bound, they are not released
What type of covalent modification provides a binding site for the proteosome?
polyubiquitination
Which enzyme adds the covalent modification required for degradation by the proteasome to a protein target?
ubiquitin ligase (E3)
Degradation of a protein can be activated by:
- changes in gene expression for a protein that interacts with the E3
- covalent modifications to a protein that interacts with the target protein
- covalent modifications to the target protein
- covalent modifications to the E3
Which protein provides the specificity in protein target selection for ubiquitylation?
ubiquitin ligase (E3)
What is the primary function of most signaling receptors?
directly sense a change, a chemical, or a macromolecule in the extracellular environment
What is the primary function of a signaling effector?
directly turn on or off a cellular process
What can be a signaling molecule?
- What can be a signaling molecule?
- a membrane protein on another cell
- amino acid
- steroid
- fatty acid
- peptide
- secreted protein
- dissolved gas
- nucleotide
A signaling receptor has to recognize a particular signal over other signals – this means that it has:
high specificity
what type of cell-cell signaling involves only one cell?
autocrine
what type of cell-cell signaling requires one cell to be proximal (close) to, but not touching, another cell?
paracrine
what type of cell-cell signaling requires a cell to be physically in touch with another cell?
contact-dependent
What attaches a phosphate group covalently to a target molecule, like a protein or a lipid?
Kinase
second messengers
- can be produced in the cytosol
- can originate from the plasma membrane
- includes small chemicals
- includes proteins
- relays a signal by diffusion away from its place of origin to other parts of the cell
What uses a trimeric complex that contains a GTPase for intracellular signaling?
a G-protein coupled receptor (GPCR)
What can be found in membranes?
- cholesterol
- receptors for chemical signals
- glycolipids
- phospholipids
- proteins that serve a structural role
- proteins that transport molecules
The endoplasmic reticulum is the main site of production for:
- Proteins that are secreted from the cell
- Transmembrane proteins found in the ER, Golgi, and plasma membranes
Match the following properties of ER localized proteins to their type (Transmembrane, Soluble, or Both).
requires an ER signal sequence for localization
Both
Match the following properties of ER localized proteins to their type (Transmembrane, Soluble, or Both).
requires SRP for localization
Both
Match the following properties of ER localized proteins to their type (Transmembrane, Soluble, or Both).
can carry a stop-transfer signal
Transmembrane
Match the following properties of ER localized proteins to their type (Transmembrane, Soluble, or Both).
can have its ER signal sequence cleaved off by signal peptidase
both
Match the following properties of ER localized proteins to their type (Transmembrane, Soluble, or Both).
can contain an internal ER signal sequence
Transmembrane
Sec61
-provides a channel for polypeptide passage into the ER lumen.
SRP
- binds to an ER membrane receptor
- composed of a non-coding RNA and protein
- binds to the ER signal sequence as it emerges from ribosomes
ER signal sequence
bound by the Sec61 complex
Signal sequences are _____
hydrophobic alpha helicies
stop-transfer sequences are _____
hydrophobic alpha helicies
When Ran is in its GTP bound form, it can bind directly to:
- nuclear import receptors
- nuclear export receptors
Proteins with NLSs are recognized by
importins
Proteins with NESs are recognized by
exportins
Nuclear transport receptors stay associated with their cargo proteins untill….
only until they are delivered to their destination
GTPases switch between two conformations, with switching enabled by
- the unassisted binding of GTP, once GDP is dissociated
- the activity of a GTPase activating protein
- the activity of a guanine nucleotide exchange factor
- GTP hydrolysis to GDP
sorting signal sequences
- can occur in an internal region of a cargo protein
- can be cut off after transport
- can be found at the tertiary level of protein structure
- are recognized by receptors that guide proteins to their destination
Gated transport
Transport between the nucleus and the cytoplasm
Transmembrane transport
transport across or into a membrane from the cytosol
Vesicular transport
Transport within membrane enclosed structures, from one membrane enclosed compartment to another
Site of membrane protein synthesis
ER
Major site of DNA and RNA synthesis
Nucleus
Main site of protein synthesis and degradation
cytosol
Site of Ca2+ storage
ER
Site of lipid synthesis
ER
Site of secreted protein synthesis
ER
receives lipids and proteins from the ER
Golgi
where material is taken up into the cell before transport to the lysosome
endosome
site of macromolecule, particle and organelle degradation
Lysosome
Composed of organized stacks of disc-like compartments
Golgi
PDI
catalyzes the formation of disulfide bonds in the ER
BiP
ATP-dependent protein chaperone, ensures that only properly folded ER localized proteins move on to the Golgi
Oligosaccharyl transferase
catalyzes the covalent addition of a sugar-containing group to ER localized proteins
During the progression of a cell surface receptor from the ER to the plasma membrane, the receptor domains that ultimately face outside of the cell are located on _________ and __________
- the ER lumen-facing side of the ER membrane
- the inside surface of transport vesicles
while the domains that ultimately face the inside of the cell are located on __________ and ________
- the cytosolic side of the ER membrane
- the outside surface of transport vesicles
What was primary advantage of using pancreatic cells in George Palade’s experiments for discerning the order and vesicle transport mechanism of the secretory pathway?
the cells produce large amounts of digestive enzymes
In the Palade pulse-chase experiments, what was labeled with radioactivity?
newly synthesized proteins
Secretory pathway (includes exocytosis) order of vesicle transport
ER -> Golgi -> Cell surface (and other organells)
Endocytosis order of vesicle transport
Cell Surface -> Endosomes -> Lysosomes (sometimes)
Retrieval pathway (also called retrograde transport) order of vesicle transport
Golgi -> ER
