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Molecular Cell Biologyseventh Edition

Chapter 13:Moving Proteins into Membranes

and Organelles

Copyright © 2013 by W. H. Freeman & Company

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Overview of major protein-sorting pathways in eukaryotic cells

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The Nobel Prize in Physiology or Medicine 1999"for the discovery that proteins have intrinsic signalsthat govern their transport and localization in the cell"

Günter BlobelUSARockefeller University New York, NY, USA; Howard Hughes Medical Institute

b. 1936(in Waltersdorf/Silesia, Germany)

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Co-translational translocation

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Major topological classes of integral membrane proteins

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Synthesis and insertion into the ER membrane of type I single-pass proteins

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Synthesis and insertion into the ER membrane of type II single-pass proteins

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Arrangement of topogenic sequences in membrane proteins

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Hydropathy profiles

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GPI anchor

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Formation of GPI-anchored proteins in the ER membrane

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Common 14-residue precursor of N-linked oligosaccharides

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Biosynthesis of the dolicol pyrophosphoryl oligosaccharide precursor of N-linked oligosaccharides

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Addition and processing of N-linked oligosaccharides in the rough ER of vertebrate cells

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Disulfide bond formation by protein disulfide isomerase (PDI) in ER

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Disulfide bond formation in periplasmic space of bacteria

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Chaperones and other ER proteins facilitate folding and assembly of proteins

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The unfolded protein response (UPR)= ER stress (ERS) response

yeast

The unfolded protein response in vertebrates

Trends Biochem Sci.2015 Mar;40(3):141-148

Homeostasisor

Death

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Vesicular Traffic, Secretion,and Endocytosis

黃敏銓

Chapter 14

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Secretory and endocytic pathways of protein sorting

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p20 NATURE CELL BIOLOGY VOLUME 14 | NUMBER 1 | JANUARY 2012

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Phenotypes of yeast sec mutants identified stages in the secretory pathway

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Vesicle buds

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Vesicle budding and fusion with a target membrane

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Assembly of a protein coat drives vesicle formation and selection of cargo molecules

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Small GTP-binding protein, Sar1, in the assembly and disassembly of COPII

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Coated vesicles accumulate in the presence of nonhydrolyzable GTP analog

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Rab GTPases control docking of vesicles on target membranes

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VAMP

Paired sets of SNARE proteins mediate fusion of vesicles with target membranes

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Membrane fusion

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Dissociation of SNARE complexes after membrane fusion is driven by ATP hydrolysis

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Early stages of the secretorypathway

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Vesicle-mediated protein trafficking between the ER and cis-Golgi

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KDEL receptor retrieves ER-resident proteins from the Golgi

Soluble protein: KDELMembrane protein: KKXX

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Anterograde and retrograde transport vesiclesAnterograde transport through the Golgi occurs by cisternal progression: procollagen aggregates

Nature. 2012 Feb 22;482(7386):474-5

Big vesicles for collagen secretion

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Later stages of the secretorypathway

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Major types of coat proteins in vesicular traffic in secretory and endocytotic pathway

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Dynamin is required for pinching off of clathrin vesicles

COPI and COPII vesicles do not require dynamin.

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GTP hydrolysis by dynamin is required for pinching off clathrin vesicles

GTP-γ-S: nonhydrolyzable derivative of GTP

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Receptor-mediated endocytosis and sorting of internalized proteins

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Nat Rev Mol Cell Biol. 2011 Jul 22;12(8):517-33

Signaling?

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ESCRT (Endosomal Sorting Complex Required for Transport) machinery consists of the five protein complexes ESCRT-0, ESCRT-I, ESCRT-II, ESCRT-III and Vps4-Vta1, and several ESCRT-associated proteins

J. Cell Sci. 2009. 122:2163

ESCRT complexes

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Ectosomes and exosomes

Available online 12 February 2015Trends Cell Biol.

ESCRT