Class Notes (1,100,000)
CA (620,000)
UTSG (50,000)
BIO (2,000)
BIO120H1 (1,000)

Notes taken during lecture

Course Code
Jean Jiang Nash

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Protein sorting through the secretory pathway
Transfer of proteins into ER lumen
ER has translocators embedded in membrane allow for proteins into lumen
From rough ER to Golgi apparatus to other organelles through vesicles
ER first in pathway
Proteins synthesized into lumen of ER become part of inside of lysosome or inside of ER or
secreted outside of cell
Lumenal leaflet is similar to extracellular face of cell
ER is dynamic, a network of tubules that form connections and break old ones
Protein sorting to the ER
In drawining mRNA in blue and green ribosome; nascent polypeptide
synthesizing ER signal sequence first translated
Synthesis and modification of proteins
Synthesis of lipids (smooth ER
Have ER signal sequence
mRNA +ribosomes
Constantly coming to ER membrane and then leaving
Hydrophobic amino acids at N-terminus
Model: Protein sorting
Bind GTP
Low affinity
High affinity
Receptor embedded in the membrane
Translocon in blue
Gated channel
oClosed until ribosome is bound to it, translaiting protein into lumen of ER
Prevent diffusion of ions, small molecules
GTP hydrolysis
Complex dissociates
The red signal sequence remains there in the membrane
ER signal sequence
Start-transfer sequence
Cleaves ER signal sequence
oEventully degraded
Translocator gated in 2nd direction
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