Cell biology Flashcards
1
Q
Sec-12
A
- guanine nucleotide exchange factor GEF that interconverts Sar1-GDP and Sar1-GTP
2
Q
Sar-1
A
- initiates budding COP2
- activated when GTP is bound in exchange for GDP via action of Sec12p
- switching it from a soluble to a membrane bound form by causing a conformational change which exposes a hydrophilic tail⇒ becomes embedded in ER membrane to form a focal point for vesicle assembly
- hydrolysis of GTP by Sar-1 causes release of coat proteins
3
Q
ARF
A
- ADP-ribosylation factor
- GTPase involved in formation of COP1 and also clathrin-coated vesicle
4
Q
Coat proteins
A
- family of proteins found in coates vesicles
- different transport vesicles have different complements of coat proteins
- bind to Sar-1 GTP
5
Q
RAB proteins
A
- vesicle targeting is achieved by attachment of Rab molecules to vesicles
- they are active when GTP is bound
- small monomeric GTPases that attach to the cytosolic faces of budding vesicles in the GTP-bound state and are also present on acceptor membrane
- Rab-GDP molecules in cytosol are switched to Rab-GTP by specific GEF
- Rab effector proteins on target membranes bind to Rab-GTP, but not Rab-GDP molecules, thus tethering the vesicles to the membranes
6
Q
RAB effector proteins
A
- Rab effector proteins on target membranes bind to Rab-GTP, but not Rab-GDP molecule, thus tethering the vesicles to the membranes
7
Q
SNARE
A
- v-SNARE pair with cognate t-SNAREs in the target membrane to dock the vesicle and initiate fusion
- one v-SNARE in the vesicle pairs with 3 t-SNAREs on the acceptor membrane to form a tight four-helix bundle
8
Q
Alpha-SNAP
A
- soluble NSF attachment protein
- along with NSF this protein is involved in dissociation of SNARE complex
9
Q
NSF
A
- N-ethylmaleimide-sensitive factor
- NSF hydrolyses ATP and the energy released dissociates the four-helix bundle making the SNARE proteins available for another round of membrane fusion
