Traffic Membranaire 2: Flashcards
TRUE or FALSE,
SNARE protein binding is ATP dependent/
FALSE,
Does not really require ATP to bind the SNAREs, but need ATP to recycle them
Steps in SNARE mediated fusion?
Process mediated via RAB-GTP proteins
Tethering
Docking (using tether proteins)
Fusion
What is rab?
RAB is a membrane tag that tags the membrane for proper transport fusion etc
How can the phospholipid membrane be a transport tag?
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
________________________ 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
Le réticulum endoplasmique
lisse (REL)
rugueuse (RER)
ribosomes
de membranes
Role of lisse (REL) réticulum endoplasmique?
Synthèse lipidique
Ca+ Reserve (for muscles)
Role of rugueuse (RER) réticulum endoplasmique?
bound to ribosomes:
Synthèse protéique
site of mRNA transduction into proteins
Contrôle de qualité
Glycosylation des protéines
La synthèse protéique est la traduction d’un ARNm en protéine.
Le ribosome se déplace de _________ en “lisant” chaque codon
de __________________.
5’ à 3’
3 nucléotides
What are Polysomes?
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.
Les ribosomes libres versus ceux au RE?
**libres ** : protéines cytosoliques
(ou nucléaire, ou
mitochondriale etc..)
RE: protéines destinées à
être sécrétées ou transmembranaire ou qui
fonctionnent dans le système endomembranaire
SRP, what it is and what it does?
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
WHich end of the mRNA is translated first?
the N end!!!!!!
How does a protein bind through the bicouche lipidique?
protéines transmembranaires sont
insérées dans la bicouche lipidique via le
translocon
What are Précurseurs du glycocalyx?
- Glycocalyx process begins at the ER
N-glycosylation –> Attaches 3 GLUCOSE
What is calnexine and funcion?
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
What is «Unfolded Protein Response (UPR)»: ?
«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
What happens to proteins that remain missfolded in the ER?
If a protein remains not well folded after this process → retro translocation of proteins → ubiquitination of proteins → proteasomes → degradation by proteosomes, lysosomes
What are the parts of the golgi?
cis
mediane
transe
Enter via the cis, exit via the trans region
Role of golgi in protein syntehsis?
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
What is KDEL?
THE TAGGING THAT SENDS MIS-FOLDED PROTEINS FROM THE GOLGI TO THE ER (BACK; retrograde) IS KDEL
Recruits COPI → back you go
COPII vs COPI
mediate transport of proteins between golgi and ER
COPII : anterograde
COPI : retrograde
True or False,
Le tri au niveau de Golgi se produit au niveau de medial golgi:
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)
Constitutive vs Regulated Secretion? and an example
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
What is Trancytose?
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
