Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
51 Cards in this Set
- Front
- Back
"Free ribosomes" Where does translation always begin?
|
ribosomes floating in the cytoplasm performing translation. Translation of free ribosomes always begins in the cytosol
|
|
membrane bound ribosomes found where? how to they know to go there?
|
on RER outer surface. there is a targeting sequence on the N terminus telling them to go to the RER
|
|
Where are proteins/cargo carried in vesicles?
|
carried inside the vesicles, but also on/in the membrane. Can be on the inner/outer/or transmembrane.
|
|
Network of enclosed tubules with continuous lumen, continuous with nuclear envelope, largest membrane system in mammals
|
Endoplasmic recticulum-continuous SER/RER lumen
|
|
Secretory Pathway of RER
|
mRNA-Translating ribosomes-RER-Golgi-Secretory vesicles-Exterior
|
|
How do you get a protein into the RER? What is the pathway called? Envisions the steps.
|
Secretory Pathway (of RER)
-signal sequence on N terminus of growing polypeptide (first 16-30 nucleotides) is bound to by Signal Recognition Particle (SRP-6 proteins/1RNA) -Binds to Signal sequence and stalls elongation -Brings polypep to SRP receptor on surface of RER -Binding triggers release of SRP (GTPase dependent) -Translation starts again, threading the polypep through the translocon into lumen on the RER -cleaved by signal peptidase at amino terminus=secretory protein |
|
Integral Membrane Protein Types
|
Stop Transfer Sequence (STS) and Internal Signal Sequence (ISS)
|
|
Stop Transfer Sequence
|
Translocation of STS and threading when translocon recognizes a membrane-spanning domain
-stops translation and releases the polypep into the RER membrance -translation then continues and the signal sequence removed by signal peptidases |
|
Internal Signal Sequence
|
when signal sequence is located further down the polypeptide/not near the N terminal
-"internal" means inside the polypeptide, causes a switch in the C and N terminals in lumen/cytosol |
|
Multi-Pass Proteins
|
alternating ISS and STS due to multiple sequences in polypeptide. leads to looping of polypep (pp) in and out of the membrane
you can tell which region are hydrophobic by the hydropathy profile/graph |
|
N-linked Glycosylation is what?
|
adding a sugar (oligosacc) to dolichol on inner membrane of RER
|
|
Glycolipid modification to RER
|
add glycolipids to inner membrane of RER (GPI Anchors)
-GPI anchors secreted into vesicles (inner membrane) then fuse with plasma membrane-located on the outside (remember diagram) |
|
Protein Folding in RER via Chaperones. What are they? function? examples?
|
Chaperones assist in proper folding of proteins into correct tertiary structure.
ex) BiP (Hsp) and Calnexin/Calretiiculin |
|
What is Protein Disulfide Isomerase? what does it do?
|
enzyme in lumen of RER that catalyzes correct formation of disulfide bonds btw cys residues. Critical for proper protein folding.
|
|
Chaperones act as sensors for ?
|
misfolded proteins
|
|
Name/describe the 2 ways misfolded proteins can be fixed in RER
|
ERAD- misfolded proteins transported to cytosol for degradation by ubiquitin-proteosome system
Unfolded Protein Response-Stress response triggered by overload of unfolded proteins, Kinase pathwas says "stop making proteins!" |
|
Smooth endoplasmic reticulum is usually located in what kind of cells?
|
sparse in many cells but abundant in cells involved in metabolism of lipids such as steroid hormone producing cells and the sarcoplasmic reticulum
|
|
Main Function of SER
|
Synth of Lipids (on cytosolic side)
Calcium Storage/Release (SR) Glycogen metabolism (Glucose 6-phosphate in liver SER) Drug Detoxifcation (Liver) |
|
Synthesis of Lipids in the SER: makes what and where on the SER?
|
makes phospholipids, cholesterol, ceramide on the cytosolic side of the SER via cytosolic enzymes. They are built into the outer leaflets of SER and flippasses bring them inside
|
|
Flippases do what?
|
switch lipids onto the other side of a membrane
|
|
Golgi structure/nickname
|
"Fedex", stacks of cisternae=membrance bound sacs that transport vesicles
has cis network/medial network/trans network -cis=convex/toward nucleus/entry face -trans=concave/exit face |
|
Function of Golgi
|
Protein Processing
|
|
Cis Golgi Network does what? TEST DAY
|
phophorylation of N-lnked Oligosacc(which is made in the ER), with mannose-6-phosphate (which tags proteins to go to lysosomes to help digest stuff)
shipped to Golgi, while moving thru golgi, enzymes remove mannoses and add other residues ="Trimming decorating of xmas tree) (mannose 6-phosphate) |
|
Golgi Cisternae do what? TEST DAY!
|
Modify N-linked Oligosacc by:
-removal of mannose and -addition of residues and addition of O-linked Oligosacc |
|
trans golgi network does what?
|
sulfation of proteins on tyrosine
|
|
Phosphorylation of N-Oligosaccarides tags proteins to go/become what?
|
tags proteins to go to lysomes and become lysosomal enzymes.
mannose is tagged by phosphate |
|
O-linked gycosylation of Proteins. TEST DAY!!!
|
Sugars are added to Ser, Thr, or Tyr
-added one at a time in the cis/medial cisternae "O"ne at a time. added to ser-thr. Tyrosine. |
|
Sulfation of proteins in Golgi
|
sulfate group is added to Tyr residue
-occurs mainly in trans Golgi network |
|
Synth of Sphinomyelin and Glycolipids
|
synthed from ceramind in lumen of golgi-move to organeeles via budding of vesicles
|
|
Types of Secretion from the Golgi (3 types)
|
Constitutive, Regulated Secretion, Lysosomal
|
|
Consitituive Secretion from Golgi
|
constantly on/secreting things the cell always needs/is making ex) ECM or basal lamina
|
|
Regulated Secretion from Golgi
|
vesicles only released in response to stimulus
ex) neurotransmitter -exits golgi via clatherin-coated vesicles to for immature secretory granules -excess membrane recycle+concentrated cargo in as little membrane as possible exocytosis via specific signals/stimulus |
|
Lysosome pathway
|
Lysosomal enzymes tagged with mannose 6 phos and exit the trans golgi via budding of clatherin coated vesicles
|
|
Vesicular Trafficking has what kinds of transport?
|
Anterograde (COPII) and Retrograde (COPI) vesicles
|
|
COPII
|
the messy COP (hutch)
goes from RER to cis golgi or tubular vesicles network (anterograde/spreading out) |
|
COPI
|
the neat cop (starsky)
trans to cis golgi vesicles to RER (retrograde/cleaning up) |
|
Clatherin-coated vesicles
|
transport in both directions btw the trans golgi and other cell compartments
|
|
Budding of Transport Vesicles: transmembrane proteins contain specific AA sequence that functions as a _______ for ______ and _____
|
sorting signal for retention and export
|
|
Transport vesicles bud from membranes as...?
|
coated vesicles
|
|
what binds to sorting signals and the coat during vesicles budding?
what do they do? |
adaptor proteins
they couple the transmembrane protein to the protein coat of the budding vesicle |
|
Adaptor proteins are _____ proteins
|
specific
|
|
Dynamin is/does what?
|
GTPase that pinches off the budding transport vesicle
|
|
Activity of adaptor proteins is regulated by? give 2 examples
|
GTP binding proteins ex) ART and Rab
|
|
After the transport vesicle buds off into cytoplasm, the coat ______ so that?
|
dissolves so that the vesicle can recognize/fuse with correct target membrane
|
|
Receptor on PROTEIN that connects to clatherin coat through adaptor protein.
used to mark what? |
Mannose 6-P
lysosomal enzymes |
|
What has to happen to expose proteins on the surface of the transport vesicle?
|
the coat+adaptor proteins have to be dissolved
|
|
Vesicular Fusion: What is recruited to membrance and interacts with the effector proteins?
|
Rab-GTP
|
|
Name the 2 proteins used on the surface of vesicular fusion and their function
|
v-SNARE (vesicle specific protein) and t-SNARE (target specific protein)
get tethered together to help facilitate fusion |
|
What does the effector protein do during vesicular fusion?
What results of this action? byproduct? |
it finds the targeting receptor, binds to it, and tethers the SNARE proteins together as a result. This leads to the GTP hydrolysis and membrane fusion
|
|
How many membranes does a protein pass after translation?
|
1
secretory protein technically is always inside one membrane or another all the way through sorting until it is secreted into the Extracellular space |
|
Secretory Granules follow what type of export system? what do they look like?
|
same system as export of vesicles. look like "bullseyes"
|