Master course Molecular & Cellular Life Sciences Part 1: Intracellular Membrane Processes October 8,...
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Transcript of Master course Molecular & Cellular Life Sciences Part 1: Intracellular Membrane Processes October 8,...
Master course Molecular & Cellular Life Sciences
Part 1: Intracellular Membrane Processes
October 8, 2009
Paul van Bergen en Henegouwen
Mechanisms of clathrin-independent
internalization
Paul van Bergen en Henegouwen
Different endocytic portals
Characteristics
Endocytosis: what’s the problem?
bending fission
Five ways to bend a membrane
Clathrin-dependent internalization
Clathrin-coated and vesicles:Ultrathin section of plastic-embedded material
Clathrin-coated pits and vesicles by EMReplica of freeze-dried plasma membranes
Clathrin-coated vesicles:Replica of freeze-dried plasma membranes
Clathrin: Heavy- and light chains
Clathrin makes a network
How clathrin is bending?
AP-2Adaptor Protein-2 complex
a b2m2
s2
EarHinge
Trunk
100 kDa
50 kDa
17 kDa
a-adaptin b-adaptin
There are different AP-complexes on different sites in the cell
Golgi-complex Plasma membrane Golgi-complex
a b2m2
s2g b1m1
s1d b3
m3
s3
AP-1 AP-2 AP-3
Protein/protein interactions control CCV formation
a b2m2s2
Receptor
Yxxf
Eps15
DPF
Receptor
LL
LfxfD/E
Clathrin
AP-2
I
EHs
II
COIL
III
DPF/UIM
Epsin
NPF
Lipids
DPW
PIP2
Epsin induces bendingof liposomes
The netwerk forms a ballElectron tomography of a coated vesicle
Adaptor protein(AP2) complex
s chain m chain
b adaptin
a adaptin
Clathrin triskelion
Smith et al. (1998) EMBO J. 17, 4943
Overview of clathrin structures
Marsh and McMahon (1999) Science 285, 215-220
From bending to fission
Dynamin, a GTPase involved in fission
PIP2 Amphiphysin
Dynamin is forming a ring around the neck
Effect of pure dynamin on lipid vesicles
PIPK
Membrane curvature generation
AP2ClathrinEps15
IntersectinAmphiphysinEpsin Dynamin
Endophilin
Moleculen involved in the whole process
Possible role for actin filaments
PIPK
Membrane curvature generation
AP2ClathrinEps15
IntersectinAmphiphysinEpsin Dynamin
Endophilin
Actin
SynaptojaninAuxilinHsc70
Moleculen involved in the whole process
Overview of all interactions
EGFR internalization via a non-coated pathway!
Is the alternative route visible?
Caveolae
Caveolin
Caveolar internalization starting from cholesterol-rich domains
Trafficking of Caveolae
Phagocytosis:Internalization of large items
Overview of different internalization routes
Properties of different CI-routes
Classification of internalization routes
Questions
What does the bending?What does the fission?
Interleukin-2 receptor complex
IL-2R internalization is Clathrin-independent clathrin-inhibition by ΔEps15
IL-2R internalization is Dynamin-dependentDynamin-inhibition by Dyn-K44
TfR
wt
K44A
IL-2R is present in the Detergent Resistant Membrane (DRM) fraction