Lecture 10 Flashcards
Three types of cotaed vesicles?
- COP I
- COP II
- Clathrin coated vesicles
COP I
Golgi to ER (Anterograde)
COP II
ER to Golgi (retrograde )
CCV
Transport from golgi/PM to the endosomes
Initiator proteins of COP-I and COP-II ?
RAS GTPases
Ras GTP vs Ras GDP
Active, inactive
GAPs?
Aid in switching Ras GTP to Ras GDP (active to inactive form)
GEFs?
Aid in switching Ras GDP to Ras GTP
(inactive to active form)
Release GDP and bind GTP
COP I and COPII specfic Ras GTPases?
COP II: Sar1
COP I: Arf1
COP II proteins?
Initiator: Sar 1-GTP
Adaptor Proteins: Sec23, Sec24
Coat Proteins: Sec13, Sec31
ER Exit Signal?
Allows protein from ER to be actively recruited to vesicles
Transmembrane Protein Exit Signals?
-Found on the cytosolic side
-FF at C-terminus
-DXE within a sequence
- Recognized by Sec23 and Sec24
Lumenal Protein Exit Signals?
-Bind to cargo receptors which have FF at their C-terminus
Bulk Exit
Stuff floating in the ER picked up by COP II vesicles, stuff we don’t want is transported back via COP I vesicles to the ER
ER Retrieval Signals of transmembrane proteins?
-KKXX at cytosolic C-terminus(Type 1 TM)
-MXXRR signal at the cytosolic N-terminus (Type 2 TM)
ER Retrieval Signals of Lumenal Proteins?
-KDEL recognized by the cargo receptor with a KKXX motif
COP I proteins?
Initiator: Arf1-GTP
Adaptor Proteins: beta/gamma and delta/zeta subunits
Coat protein: alpha/beta’
CCV initiator?
Phosphatidylinositol
Phosphatidylinositol phosphorylation?
Different sugar groups can be phosphorylated converting PI to PIP
-each organelle has different kinases to phosphorylate PI differently
PI
Sugar ring with no phosphorylations
PI(3,4)P₂
Phosphorylation on groups 3 and 4 of the sugar ring, subscript 2 = two phosphates total
T/F: difference in phosphorylation creates a different shape in the PIP which is what allows us to recruit different effectors
True
PIP budding off PM?
PI(4.5)P₂
PIP budding of Golgi?
PI(4)P
CCV Adaptors?
AP-1 and AP-2 these bind to PI(4.5)P₂ in the PM and cargo. They then recruit clathrin coat proteins
Clathrin Triskelions?
3 large and 3 light subunits form a coated pit around the vesicle
CCV fission?
Dynamin (GTPase) associates near the closure point of the vesicle during CCV assembly. Dynamin are bound to GTP when they hydrolyze they twist and constrict pinching off the vesicle
Auxillin
-j domain and clathrin binding domain (HSC70)
-Binds clathrin then recruits HSC70 to remove the coat
