chapter 14.1-14.4 Flashcards
how do proteins flow through the Golgi complex
cis to medial to trans golgi (normally)
what are GTPases
enzymes that bind GTP and hydrolyze it to GDP
how does GTPase work
when bound to GTP, the protein adopts the “on” conformation and it can interact with target proteins to regulate their activities
what does GEF do
mediates the exchange of the bound GDP with a GTP molecule in the GTPase switch
what do GAPS do
influence the rate of GTP hydrolysis in the GTPase switch
what 3 things are essential for vesicles
coat, GTPase, V-snare
what are the main three types of vesicles
COPII and COPI, clathrin
how does COPII mediate flow
ER to cis-golgi
how does COPI mediate flow
cis-golgi to ER later to earlier
how does clathrin proteins mediate flow
trans-golgi to endosome, plasma membrane to endosome, golgi to lysosome, melanosome, platelet vesicles
what is the role of GTPase in the formation of the COPII coats
GTPase binds to the membrane and GDP is exchanged at Sec12 for GTP and the hydrophobic N-terminus end of the GTPase is inserted into the membrane
once GTPase is in the ER membrane, what happens
Sec23/24 come and bind on the outside edge, forming the coat
what happens to the coat when GTP is hydrolyzed
the coat disassembles
what does V snare do
associates with T-snare on the target membrane, pulling the vesicle close to the target membrane
what is anterograde transport
transport from the ER to the golgi
what is retrograde transport
transport from the Golgi back to the ER
what role does KDEL receptor/signal play
KDEL signal is associated with ER proteins and the KDEL receptor recognizes this, binds the protein and travels back to the rough ER in a COPI vesicle
what supports golgi cisternal maturation
COPI-coated vesicles transport vesicles carrying ER/golgi-resident proteins in the retrograde direction
what part of the golgi sends proteins to where they’re supposed to go
the trans-golgi network sorts proteins into vesicles targeted for different destinations
how do proteins get to the lysosome
lysosomal enzymes bear M6P residues that are recognized by M6P-receptors and delivered by a clathrin-coated vesicle pathway to the lysosomes
what is the structure of clathrin coats
triskelion structure that buds from the trans-golgi and plasma membranes
what do M6P residues do
direct newly synthesized lysosomal enzymes to lysosomes
M6P targeting signal addition by
two cis-golgi resident enzymes
what are proproteins
proteins that are matured into final form after leaving the trans-golgi
