Midterm 3- Pain Flashcards
Role of the Golgi
Sorts membrane lipids and processes incoming proteins via O glycosolation and pruning of carbohydrate side chains
Role of the two sides of the Golgi
Trans side- Associates with the plasma membrane and sorts and sends mature proteins for usage
Cis side- Sorts incoming proteins from the ER
Terminal glycosolation
Modification of the glycoprotiens through the removal or addition of sugars on the core oligliosaccharide within the lumen of the golgi
Importance of glycosolation process on proteins
1) Used in protein sorting
2)Helps create resistance against protease digestion
3)Used in cell cell recognition
4)Participation in regulation of immune cells
Two hypothesis for Golgi movement
1) Stationary cisternae model: Cisternae and enzymes stay in place while cargo moves in vesicles
2)Cisternal Maturation Model: Each layer of the cisternae matures from the cis towards the trans side of the Golgi carrying its cargo with it with the vesicles moving Golgi proteins between different maturation phases of the golgi
Anterograde
Movement of proteins forward in the golgi from cis to trans face, similar to exocytosis
Retrograde
Movement of protiens backwards in the golgi from trans to cis face, similar to endocytosis
Which studies support which Golgi theory
TEM- Cisternal maturation
Inhibition ER transport- Cisternal maturation
Florescence microscopy- Stationary Golgi
Two pathways for ensuring proper drop off of proteins to organelles
1)Retention tagging: when in the correct environment protein has low affinity for vesicles to transport it again
2)Retrieval tag: Tags that when read will lead to escaped protein being sent to proper location
Soluble ER specific protein tags
KDEL (Lys,Asp,Glu,Leu) is added to the C terminus of the protein and mediates return of proteins back to the ER
ER specific transmembrane protein tag
KKXX(Lys,Lys,any,any) found on their cytosolic domains that signal for a return back to the ER
KDEL retrieval process
1) Escaped KDEL molecules bind to KDEL receptors in the golgi
2)KDEL receptors begin aggregating escaped proteins and form a vesicle which will return them to the ER
3)At the ER the high Ph causes the KDEL receptors to dissociate from the proteins and returns to golgi
Lysosomes targeting tag
Phosphorylation of the mannose side chain creates the Mannose-6-phosphate tag which when read leads to proteins being delivered to lysosomes
Role of protein coats in vesicle transport
1)Curve the membrane to form the actual vesicle structure
2)select the components that will be carried in the vesicle
The layers of the vesicle and their function
1)Outer: Scaffolding for the vesicle
2)Inner: Contains adapters which bind to specific proteins and hold the outerlayer and the contents together
Three vesicle classes and their direction of transport
1)COPII- ER to endo ERGIC and golgi complex(Anterograde)
2)COPi- ERGIC and Golgi back to ER- retrograde
3)Clatherin Coated- plasma membrane to golgi
Send off of vesicle bud
1)Sar1 is turned from GDP to GTP causig SAR1 to insert its alpha helix into the membrane
2)After insertion SAR1 can recruit sec23 and 24 which form the inner membrane and begin the bending and V-snares embed inside
3)Sec 13 and 31 bind to form the vesicle outer later
4)Budding vesicle seperates from the ER
Receival of vesicle bud
1)Before ariving GTP is converted back into GDP on SAR1 allowing the sec proteins to dissociate
2) At destination contact of vesicle and target causes tethers proteins to pull them to port
3)RAB GDP becomes GTP recruiting the cytosolic tether proteins to allow docking
4)T-snare attaches to V-snare allowing the vesicle and target membrane to be pulled apart and fused
Dissociation of the V and T snares
NSF (N-ethylmalemide-sensitive factor) and SNAPs (soluble NSF attachment proteins) “pry apart” the SNAREs, using energy from ATP hydrolysis
Exocytosis
Vesicles content are release into an interior via fusion of a vesicle and membrane, exports
Endocytosis
Imports extracellular molecules via vesicle formation
3 types of exocytosis
1)Regulated secretion:Secretory vesicles accumulate until a chemical trigger for release
2)Polarize secretion: Secretion in one direction with localized binding
3)Constitutive secretion:unregulated continuous process of secretion
3 types of endocytosis
1)Bulk phase endocytosis: non specific movement of material into the cell
2)Receptor mediated endocytosis: Uses receptors to determine what to bring inside
3)Phagocytosis: Engulfing of large objects
Process of endocytosis
1)Specific moleules bind to a receptor on the outer leaflet
2)Lateral diffusion to clathern coated puts which concentrate receptors
3)Accumulation causes clathern buildup causing invagination to occur
4)Pit is pinched off via Dynamin ring
Difference between the structure of COP vs Clatherin
COP proteins lack overlapping segments of protiens
Adapter 2 protein
promotes the assembly of clathrin cage and recruitment of membrane receptors to the budding vesicle
Phosphoinositide
binding changes the conformation of AP2, making the cargo binding site accessible
Phagocytosis
1)Contact with target triggers plasma membrane to fold upwards and wrap around the object forming a phagosome
2)Fusion of the phagosome with a lysosome/endosome to degrade the target
Lysosomes life cycle
1)Endocrytic vesicle: Bud formed from endocytosis
3)Early endosome:Sorting of bud content, tags for degredation or recyling
4)Late endosome: acid hydrolyse present but not at proper ph
5)Lysosome:Actively digestion endosome which occurs via transformation or fusion
House keeping receptors
Uptake of material to be used by the cell, delivering them to early endosomes then returning to the cell membrane
Signalling receptors
Change activity of the cells, are degraded to reduce sensitivity of the cell to future stimulation
Residual body
Left over indigestible byproduct of endocytosis, either removed or accumulated which signals for cell death
Autophagy
Digestion of old organelles and cell structures for small particles 1 small vacuole is used and for larger objects a double wrapped membrane formed from the ER is used
PTS-1 tag
Signals for proteins to move to the peroxisome
Presequence
Signals for movement of protiens into the matrix of the mitochondria
Internal targeting sequence
Signals for movement of proteins into the inner membrane of the mitochondria
Movement of proteins into mitochondrial matrix
1)Protien is bound to chaperones to keep the protien unfolded
2) Presequences bind receptor component of TOM positioning the protein into the TOM channel
3)TOM and TIM23 are brought together
4)Electrical potential moves the peptide into the matrix
5)Protein is pulled into matrix and the presequence is cleaved allowing it to refold into the proper conformation
How to move proteins into the inner membrane of the mitochondria
1)Chaperons keep protein in unfolded state
2)Presequence binds TOM to enter the TOM channel
3)TOM and TIM22 are brought together allowing proteins to enter the bilayer
How do proteins get into the chloroplast
Use of the TIC and TOC channels, when marked with Thalakoid transfer protein, protein moves to thalakoid
RAN GEF
turns GDP into GTP and is found inside the nucleus
RAN GAP
Turns GTP into GDP and found outside of the nucleus
Importing into the nucleus
1)Importin binds to NLS and mediates movement of protein to the pore
2)Importin proteins dock with NPC and transport it into the nucleus
3)In the nucleus importin attaches to RAN allowing it to unbind to the protien
4)RAN-GTP and Importin is moved back to cytosol
5)Importin is released and GTP is hydrolzyed
Exporting from the nucleus
1)RAN-GTP binds to exportin
2)RAN-GTP_exportin complex binds NES protien
3)Export occurs
4)GTP is hydrolyzed and protein is released
5)Exportin returns to the nucleus
NLS
Nuclear localization signal, signals for movement of proteins into the nucleus
NES
Nuclear export signal, signals for movement of proteins out of the nucleus
RER proteins
1)Secreted proteins
2)Transmembrane proteins
3)Soluble proteins for the ER, Golgi, Lysosomes,endosomes,vesicles, and vacuole
Free ribsome proteins
1)Proteins that stay in the cytosol
2)Peripheral proteins for the cytosolic membrane
3)Nucleus proteins
4)Peroxisome,chloroplast and mitochondria proteins
Co-Translational import
Carry the ER signal sequence which tells the ribsomes to move into the ER to complete translation
Post translational Import
Lack the ER signal sequence and are completed on the ribosomes then are tagged afterwards to be moved into the correct organelle
Signal recognition protein usage
1) At the end of synthesis the ER signal sequence will bind the SRP
2)SRP receptors bind SRP on the surface of the ER membrane adjacent the translocon
3)SRP is released and ER signal inserts itself into the translocon
4)Translocon and ER signal trigger dislodge of the plug allowing contact into the ER lumen
5)Inside the ER lumen the chaperon protein will bind to the poly peptide and pulled into the membrane dissociating the ribosome
Type 1 single pass protein
N terminus in lumen and c terminus in cytosol
Type 2 single pass protein
C terminus in lumen and N terminus in Cytosol
Three roles of the ER
1)ER modification with N linked glycosolation
2)Quality control of proteins
3)Lipid synthesis
Describe process of N glycoslation
1)Built on cystolic side
2)Flipped to lumenal side
3)3 sugars are added (3 glucose)
4) Dolychol pyrophosphate adds it to the polypetide chain
5) then three glucose and 1 manose is removed and the molecule is sent to the GOLGI
Clarexin and Calrecticulin
Bind to N linked olligliosachharides to prevent aggregation, when the three glucose groups are removed then it will unbind
BIP
Binding protein responsible for preventing hydrophobic regions form interacting, if folded wrong BIP binds again
PDI
catalyzes disfulfide bond formation in the lumen of the ER and transfers its own sulphide bonds to the protein, regenerated with ER01
Quality control of the ER
1)Phosphorlate translation factors-Inhibit protein synthesis
2)Upregulate expression- Fix misfolds, transport proteins out of the ER and degrade proteins
ERAD
Unfolding protein response, signals for exported proteins to get jamed into the death machine
Proteosome
Large protein degradation structures that bind to ubiquiten labled proteins which removes them and breaks down the proteins into amino acids at the cost of ATP
Ubiqueten
Joined to target proteins to signal for repair or degradation
