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Lecture 8

Lecture 8

Course Code
Darrel Desveaux

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Lecture 8
Intracellular Vesicular Transport Part 2: Sorting and Packaging in the Golgi
Cargo From ER to Cis Golgi Network
oCargo packaged in COPII-coated vesicles
Bud from ER exit sites
oCargo signals?
Exit signal
Bound by cargo receptors
Other cargo have no exit signal, but are packaged because
of [high] in ER
oCOPII-coated vesicles bud from ER exit site
Shed COPII coat (mature vesicle)
Fuse with each other to form vesicular tubular clusters
oVesicular tubular clusters move to Golgi apparatus by
Retrieval (Retrograde) Transport
oRetrieval transport: COPI-coated vesicles
Vesicles from vesicular tubular clusters and Golgi to ER
oVesicles contain:
Escaped ER resident proteins
Proteins involved in vesicle budding from ER
Retrieval of ER-resident Proteins From the Golgi
oMany ER resident proteins have ER retrieval signals
oSoluble ER proteins
Signal = KDEL
Bound by KDEL receptors
Packaged into COPI-coated transport vesicles
oER membrane proteins
Example of signal = KKXX at C-terminus
Signal bound by COPI coats
Packaged into vesicles
Retrieval of ER-resident Proteins From the Golgi
oKDEL receptor cycles between ER and Golgi
Vesicular tubular clusters, Golgi high affinity for
ER low affinity for KDEL
oRegulated by pH (V-type ATPase H pump)
Binds in acidic pH; releases in neutral pH
oGolgi is more acidic than ER
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