The Hosts I: Eukaryotic Cell STructure and Function Flashcards
Describe the components used for intracellular trafficking & Understand and explain how motifs enable protein translocation and trafficking (30 cards)
What is Regulated Secretion?
Vesicles that bing to the cell membrane release cargo proteins from an external stimuli
Example of Regulated Secretion
digestive enzymes
How do mRNA vaccinations work?
- nanoparticle releases mRNA into cell, which is then translated on host ribosomes.
- Protein signals guide to secretory pathway.
- protein is presented at the cell surface for immune surveillance and activation
Outline the process of the secretory pathway:
- proteins destined for the PM contain signal sequence at the N terminus.
- Enter the Endoplasmic Reticulum, may be modified or Glycosylated.
- Bud from vesicles and go into the cis face of the Golgi Body, may be additionally modified within the golgi.
- Exit via the trans face of the golgi body with signal motif on final destination- localisation
I.T- What is residency?
Proteins made in the ER that may also have functions elsewhere, such as the golgi apparatus. These are identified by protein receptors which guide to the new location of use.
I.T.- What is Secretion?
Molecules, such as antibodies and cytokines are expelled into the extracellular environment via transport vesicles.
What is an example of required upon stimulation?
hormone release
What are the reasons behind intracellular transport?
Residency, secretion and required upon stimulation responses.
What is intracellular transport?
the highly regulated and dynamic process which moves constituents in and out of the cell.
How is intracellular transport mediated?
receptors and signalling proteins within phospholipid bilayer composition.
Where is the protein localised to if the motif is on the N-terminus?
The protein is localised to the lumen of the ER
Where is the protein localised to if the motif is on the C-terminus?
The protein is localised for staying within the ER
What is a NLS, and where is it found on the protein?
A NLS is a nuclear localisation motif, and it can be anywhere on the protein. This helps for recycling when the protein has reached the nucleus
What properties leads to higher affinity between a localised protein and the lumen of the PM or ER?
hydrophobicity
Highlight the 6 steps of ER import
- Signal sequence at N Terminus
- bonds to translocation
- signal cleaved by signal peptidase
- IF multiple hydrophobic regions, the protein will embed itself multiple times - “transmembrane domain”
- proteins becomes tightly associated with membrane
Which COP is associated with antergrade? (forward?)
COPII
Which COP is associated with reterograde?
COPI
What is a COP?
A Coatomer Protein used to faciliate backward and forward movement of proteins within the early secretory pathway
Describe the 2 processes of COPI-mediated ER retrieval
- exposed KDEL luminal protein (at c-terminus) is recognised by KDEL receptor
- Exposed (and changed) KDEL receptor interacts with COPI to make recognisable
OR - membrane bound proteins with KKXX motif at c-terminus interact with KKXX receptor and bind directly to COPI, signalling a vesicle for transport
highlight the key players of Cargo transfer via membrane fusion
Vesicle SNARE, target SNARE, Rab-GtP, Rab-effector (or tethering protein) and target membrane
process of Cargo tethering
- tethering (V-snare on outer membrane of vesicle, alongside Rab GTP)
- Docking (rab effector attaches to Rab GTP)
3.DOCKING- v-snare fuses with membrane embedded t snare - FUSION- vesicle fuses to membrane and releases cargo into cell
What structure on viruses allows them to use endocytosis?
viral receptors on outside of the cell are analogous to snare proteins and are hence accepted into the cell
What is the role of the Golgi Body?
Glycosylation plays a role in the localisation, function and recognition of proteins, and hence modifies glycans for secretion
What is the function of the cis-Golgi network
To sort proteins, alongside the phosphorylation of oligosaccharides on lysosomal proteins
