Lecture 12 10

Lecture 12 10 - Lecture 12 10/31/07 Golgi Transport COPII...

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Lecture 12 10/31/07 Golgi Transport COPII coat- Anterograde Transport -Requires Sar 1 g-protein Insert into plasma membrane in GTP form (N-term stick out) recruit coat proteins Sar 1 GTP bind to membrane to make vesicle Sar 1 GDP is in cytosol Sar 1 GTP Sar 1 GDP via Sar 1 GAP, or sec 23 This causes loss of the N-term hydrophobic tail, dissociation of Sar 1 from vesicle. All other coat proteins fall off too naked vesicle, reveal V-SNARE fusion with Golgi COP I coat- Retrograde Transport -Golgi to ER transport -Important for: Protein recycling (e.g. SNARES) Retrieval of proteins that accidentally got put in vesicles sent to Golgi Return of proteins that traveled to Golgi for modifications -Signals for retrograde transport- proteins have specific amino acid sequence that designate them to return to ER, designate them as ER resident proteins These signals are on C-terminus Luminal proteins: KDEL – interact with KDEL receptors Transmembrane proteins- KKXX – dilysine motif, interacts with COPI coat -COPI coat recruited by g-protein ARF ARF GDP ARF GTP by GEF Donor compartment is Golgi ARF is inserted into membrane by myristoylated group, which is a 14 Carbon saturated fatty acid tail o Insertion: ARF GDP ARF GTP, Myristoylated tail exposed, ARF associate with membrane, hydrophobic tail insert into normal lipid bilayer of Golgi o When ARF locate to Golgi, recruit COPI coat COPI coat consists of 7 proteins
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Lecture 12 10 - Lecture 12 10/31/07 Golgi Transport COPII...

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