Zaidi: Trafficking 1 Flashcards
SNARE proteins function
Catalyze fusion of vesicles with membranes
Rab proteins
Direct vesicles to specific spots on target membranes
Play central role in specificity of vesicular transport
Transport from ER
Newly synthesized proteins are packaged into COPII coated transport vesicles
Entry of cargo into vesicles is selective, proteins display exit signals of cytosolic surface which are recognized by receptors on COPII coat
Quality control of misfolded proteins in ER
Non-folded/misfolded proteins are retained in ER by binding to chaperone proteins such as BiP or Calnexin
They are then degraded
Heterotypic fusion
Fusion of vesicles from different compartments
Clarthrin subunits
3 large and 3 small subunits form triskelion
Triskelions assemble into a basket like structure that form coated pits
Retrieval pathway
Large vesicles bud off to form smaller vesicles coated with COPI
Return to ER depends on ER retrieval signals
Rab-GEF
Keeps it in active GTP-bound form. This form is tightly bound to membrane
Dissociation of SNARE pairs involves
NSF, accessory proteins and ATP
Dynamin protein function
Assembles a ring around a clathrin bud
Phosphoinositides play a major role in
Coat assembly, vesicle formation and protein trafficking
KDEL sequence
ER retrieval signal present in soluble proteins
Need KDEL receptor which packages them into COPI vesicles
Two major functions of membrane coat
Concentrates select proteins in a specialized patch for transport
Coat molds the vesicle to form a basketlike lattice that deforms the membrane and gives shape to the vesicle
PI’s control
Recruitment and binding of proteins to specific organelles/domains and regulate vesicle trafficking
Cis golgi network
Network of fused vesicular tubular clusters arriving from ER
Proteins and lipids enter golgi here
Rab-GDP dissociation inhibitor
Keeps it in inactive GDP-bound form. This form is soluble
SNARE proteins
Mediate fusion of vesicle with membrane
Clathrin coat is lost when
After vesicle formation is completed
Dynamin domains
PIP2 binding domain- tethers protein to membrane
GTPase domain- regulates rate of vesicle pinching
Golgi plays an important role in
Protein glycosylation
Rab1 location
ER and golgi complex
COPII coats
Mediate transport from ER
Active form of Rab binds
Rab effectors- motor proteins/tethering proteins present on the target membrane
Homotypic fusion
Fusion of vesicles from same compartment
KKXX sequence
ER retrieval signal present in ER membrane proteins
Interacts with COPI and packaged into COPI vesicles
HSP 70 chaperone function in vesicles
Uses ATP to peel off the coat
Vesicular tubular clusters
End product of vesicle fusion
Adaptor proteins
Form second layer between cage and membrane in clathrin coated vesicles
Bind clathrin and membrane-bound cargo receptors
t-SNAREs location
Found on target membrane
Clathrin-coated vesicles
Mediate transport from golgi apparatus and plasma membrane
Rab5 location
Early endosomes, plasma membrane, clathrin-coated vesicles
Trans golgi network
The region that allows exit of proteins and lipids to next step of secretory pathway
COPI coats
Mediate transport from golgi cisternae
BAR domains
Membrane bending proteins
Explain PI binding w/proteins
Different proteins bind with high specificity to the headgroups of particular PI’s
Rab3A location
Synaptic/secretory vesicles
Phosphinositides can undergo
Rapid cycles of phosphorylation and dephosphorylation to form various derivatives
v-SNAREs location
Found of vesicle membrane
