BI203 Lecture 17: Protein Sorting and Transport - Slides 88-104 (Vesicle Fusion, Endosomes, and Lysosomes) Flashcards
Two steps when a vesicle arrives at its destination:
docking, fusion
Vesicle docking is controlled by the ___ family of proteins.
Rab
Specific Rabs associate with specific transport vesicles & target membranes.
Rabs recruit ___ ___ ___ (MTFs).
Protein-protein interactions between ___ ___ ___ (MTFs) mediate vesicle docking at target membranes.
membrane tethering factors (MTFs)
Fusion of a transport vesicle with its target:
- The vesicle must recognize the correct ___ membrane.
- Vesicle and target membrane must ___, delivering the contents to the target organelle.
target, fuse
Interaction between transport vesicles and target membranes is mediated by ___ ___ ___ (MTFs) and small-GTP binding proteins (___ proteins).
membrane tethering factors (MTFs), Rab
Vesicle Rab proteins in the active ___ state bind membrane tethering factors.
GTP-bound
Tethering factors also bind coat proteins, and may stimulate formation of complexes between transmembrane proteins called ___.
SNAREs
Formation of complexes between vesicle and target SNAREs is required for ___.
fusion
___ pairing provides the energy to bring the two bilayers close enough to destabilize them and fuse.
SNARE-SNARE
SNARE proteins have a central coiled-coil domain.
This domain binds to other coiled-coil domains and zips the SNAREs on ___ and ___ membranes together.
This brings the 2 membranes into direct contact and leads to ___ of the lipid bilayers.
vesicle, target, fusion
Vesicle ___ and Target ___ interact with each other to form “coiled-coils”.
The coiling of the ___ around each other drives the membranes against each other.
v-SNAREs, t-SNAREs, SNAREs
Lysosomal function is dependent on an internal pH of ___.
Lysosomal ___ ___ help maintain this acidic pH.
5, proton pumps
Lysosomes need a pH of 5 because ___ ___ are only active at a pH of 5.
acid hydrolases
___ - Membrane-enclosed organelles that contain enzymes to break down all types of biological polymers.
They are the digestive system of the cell.
They can vary in size and shape depending on the materials that have been taken up for digestion.
lysosomes
Acid hydrolases are active inside the lysosome, but NOT in the ___. This is to prevent uncontrolled digestion of cell contents if the lysosome membrane breaks down.
cytoplasm
Mutations in genes that encode lysosomal degradative enzymes result in ___ ___ ___ - undegraded material accumulates in the lysosomes of affected individuals.
lysosomal storage diseases
___ ___ is caused by deficiency of glucocerebrosidase, which catalyzes hydrolysis of glucosylceramide to glucose and ceramide.
Gaucher disease
Gaucher disease is caused by deficiency of ___, which catalyzes hydrolysis of glucosylceramide to glucose and ceramide.
glucocerebrosidase
Gaucher disease is caused by deficiency of glucocerebrosidase, which catalyzes hydrolysis of glucosylceramide to ___ and ___.
glucose, ceramide
In the most common form of Gaucher disease, ___ are the only cells affected. Their function is to eliminate aged and damaged cells by phagocytosis
macrophages
Lysosomes digest material taken up from outside the cell by ___.
endocytosis
Lysosomes are formed when transport vesicles from the ___ ___ fuse with a late endosome.
Trans-Golgi Network
___ represent an intersection between the secretory pathway and the endocytic pathway.
Endosomes
___ types of endosomes.
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