Traffic Membranaire 2:

Question 1

TRUE or FALSE,

SNARE protein binding is ATP dependent/

Answer 1

FALSE,
Does not really require ATP to bind the SNAREs, but need ATP to recycle them

Question 2

Steps in SNARE mediated fusion?

Answer 2

Process mediated via RAB-GTP proteins
Tethering
Docking (using tether proteins)
Fusion

Question 3

What is rab?

Answer 3

RAB is a membrane tag that tags the membrane for proper transport fusion etc

Question 4

How can the phospholipid membrane be a transport tag?

Answer 4

Le PI est un phospholipide relativement rare du feuillet cytoplasmique, mais
extrêmement important

PI can be phosphorylated at positions 3,4,5 by kinases and phosphophatases

→ PIP3, PIP2

based on the tag that the membrane has, different path

Question 5

________________________ est un réseau de citernes ou sacs membranaires qui entour le noyau.
La surface est soit _____________ ou soit __________________ à
cause des ______________. Il est la fabrique __________________ de la
cellules

Answer 5

Le réticulum endoplasmique
lisse (REL)
rugueuse (RER)
ribosomes
de membranes

Question 6

Role of lisse (REL) réticulum endoplasmique?

Answer 6

Synthèse lipidique

Ca+ Reserve (for muscles)

Question 7

Role of rugueuse (RER) réticulum endoplasmique?

Answer 7

bound to ribosomes:

Synthèse protéique
site of mRNA transduction into proteins

Contrôle de qualité
Glycosylation des protéines

Question 8

La synthèse protéique est la traduction d’un ARNm en protéine.
Le ribosome se déplace de _________ en “lisant” chaque codon
de __________________.

Answer 8

5’ à 3’
3 nucléotides

Question 9

What are Polysomes?

Answer 9

A polysome is simply an mRNA with multiple ribosomes translating it simultaneously. They are employed in the synthesis of numerous copies of the same polypeptide.

Question 10

Les ribosomes libres versus ceux au RE?

Answer 10

**libres ** : protéines cytosoliques
(ou nucléaire, ou
mitochondriale etc..)

RE: protéines destinées à
être sécrétées ou transmembranaire ou qui
fonctionnent dans le système endomembranaire

Question 11

SRP, what it is and what it does?

Answer 11

SRP = signal recognition particle

Recognizes a ER tag on a newely transcribed protein from the ribosome -> take the compex to a SRP receptor on the ER membrane -> begin translating the RNA through the translocon canal

Question 12

WHich end of the mRNA is translated first?

Answer 12

the N end!!!!!!

Question 13

How does a protein bind through the bicouche lipidique?

Answer 13

protéines transmembranaires sont
insérées dans la bicouche lipidique via le
translocon

Question 14

What are Précurseurs du glycocalyx?

Answer 14

• Glycocalyx process begins at the ER

N-glycosylation –> Attaches 3 GLUCOSE

Question 15

What is calnexine and funcion?

Answer 15

N-glycosylation –> Attaches 3 GLUCOSE to the newly created protein in the ER

There is a quality control step in the ER:
Allows newly produced proteins to have necessary time for proper folding:

If protein is not yet folded and is bound to glucose, Chaperone Calnexine will hold the protein until there are no more glucose

If propely folded, send to golgi

Question 16

What is «Unfolded Protein Response (UPR)»: ?

Answer 16

«Unfolded Protein Response (UPR)»:

Si il y a trop de protéines mal repliées, la cellule augmente la transcription des gènes de chaperons tel que la calnexine pour
augmenter la quantité de RE

Question 17

What happens to proteins that remain missfolded in the ER?

Answer 17

If a protein remains not well folded after this process → retro translocation of proteins → ubiquitination of proteins → proteasomes → degradation by proteosomes, lysosomes

Question 18

What are the parts of the golgi?

Answer 18

cis
mediane
transe

Enter via the cis, exit via the trans region

Question 19

Role of golgi in protein syntehsis?

Answer 19

Throughout the journey in the ER there are multiple steps of glycosylation and tagging until protein is sent out

O-glycosylation
Maturation des glycosylations

Very complexe ologosaccharides

Question 20

What is KDEL?

Answer 20

THE TAGGING THAT SENDS MIS-FOLDED PROTEINS FROM THE GOLGI TO THE ER (BACK; retrograde) IS KDEL

Recruits COPI → back you go

Question 21

COPII vs COPI

Answer 21

mediate transport of proteins between golgi and ER
COPII : anterograde
COPI : retrograde

Question 22

True or False,

Le tri au niveau de Golgi se produit au niveau de medial golgi:

Answer 22

FALSE
Un tri se fait à la sortie au réseau trans-Golgien (TGN)

Le tri se fait au niveau du réseau trans Golgien (TGN, trans Golgi network)

Question 23

Constitutive vs Regulated Secretion? and an example

Answer 23

Regulated → needs signal (beta cells in pancreas)

Constitutive → protéines solubles sécrétées en permanence (par exemple: Na+/K+ ATPase)

Axonal Synapse:
All of the key components of synaptic vesicles will be delivered using the constitutive mode of secretion

The secretion of the vesicles is an example of regulated secretion

Question 24

What is Trancytose?

Answer 24

Endocytose de la membrane plasmique apicale, suivi de
transport et fusion avec la membrane plasmique basolatérale

important beacuse tight junctions dont allow any communication from one pole to another