Secretory pathways II Flashcards
_______ and _______ are moved from one compartment to another by membrane bound transport intermediates
- proteins
- lipids
A vesicle forms through
exocytosis - a portion of the membrane of the ER or other compartment and its contents (TM and cargo proteins) buds off
the vesicle is lined with a coat that is
specific for the proteins it contains and the final destination of the bud
The vesicle is transported to its destination compartment along _______ via _______
- microtubules
- motor proteins (dynein and kinesin)
The vesicle sheds its coating and membrane fusion occurs via
SNARE proteins
The contents of the vesicle are then released into
the lumen of the target compound
The major functions of the ER (5)
- Synthesis of lipids (phospholipid, ceramide and cholesterol)
- Control of cholesterol homeostasis (cholesterol sensor and synthesis)
- Synthesis of proteins on membrane-bound ribosomes
- Co-translational folding of proteins and early post-translational modifications
- quality control
Describe the co-translational translocation
step in transmembrane transport in which a peptide being synthesized on a free ribosome is transported to a translocon in the membrane of the ER. Synthesis of the growing peptide then ensues in the translocon.
List the major functions of the golgi (4)
- synthesis of complex sphingolipids fromt he ceramide backbone
- additional post-translational modifications of proteins and lipids
- proteolytic processing
- sorting of proteins and lipids for post-golgi compartments
Vesicle coats serve to assist the membrane to
change its shape in order to form a vesicle
Three main types of vesicle coats:
- clathrin
- COPI
- COPII
clathrin
transports proteins from the membrane to lysocomes or back to the plasma membrane
COPI
transports proteins from the golgi to the ER
COPII
transports proteins from the ER to the golgi
