BIOC 212 Study Guide - Midterm Guide: Motor Protein, Sec61, Prenylation
29 May 2018
School
Department
Course
Professor
Intracellular Trafficking Summary & Comparison
Compare & Contrast
• What uses GTP?
o SRP & SRP receptor, Ras family (Sar1, Arf1), Dynamin
• What uses ATP?
o Hsp70, Hsp90, chaperonins, etc.
• Targeting & modification signals/motifs
o Signals for ER exit and for ER retrieval
• HSP & UPR
o What activates them? What is the role of Chaperones? What are the
downstream consequences of transcription?
Initiation,
membrane
attachment
Signals on cargo
Pinching off
Uncoating
COP-II
• Sar1 GEF
activate Sar1
• Sar1 attaches
to membrane
through
amphipathic
helix
• Cargo receptor
accumulates
cargo proteins
• FF on C-
terminus
(cargo
receptor)
• DxE in
sequence
• Adaptor
proteins
(Sec23/Sec24)
bind activated
Sar1
• Coat proteins
(Sec13/31)
bind and shape
vesicle
• Pinches off
• Adaptor
protein = GAP;
GTP hydrolysis
acts as a timer
• GTP hydrolysis
causes
amphipathic
helix of Sar1 to
retract
• Weakens
interactions of
adaptors with
PM
• Coat is
removed
COP-I
• Same
mechanism but
using Arf1 &
different
proteins
(different
structure)
• KKxx-COO-
(KDEL
receptor for
lumenal
proteins)
• NH3+-MxxRR
• Analogous to
COP-II
• Analogous to
COP-II
CCV
• Phosphorylation
of PI by PI
kinases
• Phosphorylate
• Mono-Ub on
lysine
• AP-1 & AP-2
bind P-PI &
cargo
• PI
phosphatases
Document Summary
Initiation, membrane attachment: sar1 gef activate sar1, sar1 attaches to membrane through amphipathic helix, cargo receptor accumulates cargo proteins. Uncoating: ff on c- terminus (cargo receptor, dxe in, adaptor proteins (sec23/sec24) bind activated. Gtp hydrolysis acts as a timer: gtp hydrolysis sequence, coat proteins (sec13/31) bind and shape vesicle causes amphipathic helix of sar1 to retract, pinches off, weakens interactions of adaptors with. Pm: coat is removed, same, kkxx-coo, analogous to, analogous to. & gdf: clathrin coat binds, dynamin (gtpase) gets activated and dimerizes, gtp hydrolysis causes pinching effect remove the phosphates, auxilin binds clathrin coat, recruits hsc70, hsc70 binds coat and induces conformational change, coat breaks into triskelions. & recycled: retromer, gtp hydrolysis cargo proteins (vps) bound to cargo bind the. Gtp-rab7 of rab7 weakens interactions with adaptors: adaptors let go of snx, coat removed. Energy used for pinching off + uncoating: snx bind.
