Protein Synthesis/secretion, Golgi, Er

Front 1

"Free ribosomes" Where does translation always begin?

Back 1

ribosomes floating in the cytoplasm performing translation. Translation of free ribosomes always begins in the cytosol

Front 2

membrane bound ribosomes found where? how to they know to go there?

Back 2

on RER outer surface. there is a targeting sequence on the N terminus telling them to go to the RER

Front 3

Where are proteins/cargo carried in vesicles?

Back 3

carried inside the vesicles, but also on/in the membrane. Can be on the inner/outer/or transmembrane.

Front 4

Network of enclosed tubules with continuous lumen, continuous with nuclear envelope, largest membrane system in mammals

Back 4

Endoplasmic recticulum-continuous SER/RER lumen

Front 5

Secretory Pathway of RER

Back 5

mRNA-Translating ribosomes-RER-Golgi-Secretory vesicles-Exterior

Front 6

How do you get a protein into the RER? What is the pathway called? Envisions the steps.

Back 6

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

Front 7

Integral Membrane Protein Types

Back 7

Stop Transfer Sequence (STS) and Internal Signal Sequence (ISS)

Front 8

Stop Transfer Sequence

Back 8

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

Front 9

Internal Signal Sequence

Back 9

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

Front 10

Multi-Pass Proteins

Back 10

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

Front 11

N-linked Glycosylation is what?

Back 11

adding a sugar (oligosacc) to dolichol on inner membrane of RER

Front 12

Glycolipid modification to RER

Back 12

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)

Front 13

Protein Folding in RER via Chaperones. What are they? function? examples?

Back 13

Chaperones assist in proper folding of proteins into correct tertiary structure.

ex) BiP (Hsp) and Calnexin/Calretiiculin

Front 14

What is Protein Disulfide Isomerase? what does it do?

Back 14

enzyme in lumen of RER that catalyzes correct formation of disulfide bonds btw cys residues. Critical for proper protein folding.

Front 15

Chaperones act as sensors for ?

Back 15

misfolded proteins

Front 16

Name/describe the 2 ways misfolded proteins can be fixed in RER

Back 16

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!"

Front 17

Smooth endoplasmic reticulum is usually located in what kind of cells?

Back 17

sparse in many cells but abundant in cells involved in metabolism of lipids such as steroid hormone producing cells and the sarcoplasmic reticulum

Front 18

Main Function of SER

Back 18

Synth of Lipids (on cytosolic side)
Calcium Storage/Release (SR)
Glycogen metabolism (Glucose 6-phosphate in liver SER)
Drug Detoxifcation (Liver)

Front 19

Synthesis of Lipids in the SER: makes what and where on the SER?

Back 19

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

Front 20

Flippases do what?

Back 20

switch lipids onto the other side of a membrane

Front 21

Golgi structure/nickname

Back 21

"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

Front 22

Function of Golgi

Back 22

Protein Processing

Front 23

Cis Golgi Network does what? TEST DAY

Back 23

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)

Front 24

Golgi Cisternae do what? TEST DAY!

Back 24

Modify N-linked Oligosacc by:
-removal of mannose
and
-addition of residues and addition of O-linked Oligosacc

Front 25

trans golgi network does what?

Back 25

sulfation of proteins on tyrosine

Front 26

Phosphorylation of N-Oligosaccarides tags proteins to go/become what?

Back 26

tags proteins to go to lysomes and become lysosomal enzymes.

mannose is tagged by phosphate

Front 27

O-linked gycosylation of Proteins. TEST DAY!!!

Back 27

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.

Front 28

Sulfation of proteins in Golgi

Back 28

sulfate group is added to Tyr residue
-occurs mainly in trans Golgi network

Front 29

Synth of Sphinomyelin and Glycolipids

Back 29

synthed from ceramind in lumen of golgi-move to organeeles via budding of vesicles

Front 30

Types of Secretion from the Golgi (3 types)

Back 30

Constitutive, Regulated Secretion, Lysosomal

Front 31

Consitituive Secretion from Golgi

Back 31

constantly on/secreting things the cell always needs/is making ex) ECM or basal lamina

Front 32

Regulated Secretion from Golgi

Back 32

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

Front 33

Lysosome pathway

Back 33

Lysosomal enzymes tagged with mannose 6 phos and exit the trans golgi via budding of clatherin coated vesicles

Front 34

Vesicular Trafficking has what kinds of transport?

Back 34

Anterograde (COPII) and Retrograde (COPI) vesicles

Front 35

COPII

Back 35

the messy COP (hutch)

goes from RER to cis golgi or tubular vesicles network (anterograde/spreading out)

Front 36

COPI

Back 36

the neat cop (starsky)

trans to cis golgi vesicles to RER (retrograde/cleaning up)

Front 37

Clatherin-coated vesicles

Back 37

transport in both directions btw the trans golgi and other cell compartments

Front 38

Budding of Transport Vesicles: transmembrane proteins contain specific AA sequence that functions as a _______ for ______ and _____

Back 38

sorting signal for retention and export

Front 39

Transport vesicles bud from membranes as...?

Back 39

coated vesicles

Front 40

what binds to sorting signals and the coat during vesicles budding?

what do they do?

Back 40

adaptor proteins

they couple the transmembrane protein to the protein coat of the budding vesicle

Front 41

Adaptor proteins are _____ proteins

Back 41

specific

Front 42

Dynamin is/does what?

Back 42

GTPase that pinches off the budding transport vesicle

Front 43

Activity of adaptor proteins is regulated by? give 2 examples

Back 43

GTP binding proteins ex) ART and Rab

Front 44

After the transport vesicle buds off into cytoplasm, the coat ______ so that?

Back 44

dissolves so that the vesicle can recognize/fuse with correct target membrane

Front 45

Receptor on PROTEIN that connects to clatherin coat through adaptor protein.

used to mark what?

Back 45

Mannose 6-P

lysosomal enzymes

Front 46

What has to happen to expose proteins on the surface of the transport vesicle?

Back 46

the coat+adaptor proteins have to be dissolved

Front 47

Vesicular Fusion: What is recruited to membrance and interacts with the effector proteins?

Back 47

Rab-GTP

Front 48

Name the 2 proteins used on the surface of vesicular fusion and their function

Back 48

v-SNARE (vesicle specific protein) and t-SNARE (target specific protein)

get tethered together to help facilitate fusion

Front 49

What does the effector protein do during vesicular fusion?

What results of this action? byproduct?

Back 49

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

Front 50

How many membranes does a protein pass after translation?

Back 50

1

secretory protein technically is always inside one membrane or another all the way through sorting until it is secreted into the Extracellular space

Front 51

Secretory Granules follow what type of export system? what do they look like?

Back 51

same system as export of vesicles. look like "bullseyes"