Post on 16-Aug-2019
Volker Gerke Institute of Medical Biochemistry
ZMBE
Center for Molecular Biology of Inflammation
Membrane Biosynthesis and
Homeostasis
Biological membranes
Biological membranes
Membrane lipids
Biosynthesis of membrane lipids
Biosynthesis of glycerophospholipids
Biosynthesis of glycerophospholipids
Biosynthesis of glycerophospholipids
Biosynthesis of glycerophospholipids
The bilayer transfer problem
Synthesis at cytosolic
leaflet
Regulated lipid translocation
Ceramide
Condensation
N-acylation H2O
FA
FA
H2O
Biosynthesis of sphingolipids
CDP-cholin
Sphingomyelin
UDP-activated sugars
Glycosphingolipids
Ceramide
Biosynthesis of sphingolipids
Biosynthesis of sphingolipids
Glycosphingolipids
Biosynthesis of cholesterol
Biosynthesis of cholesterol
Cholesterol incorporation into membranesConsequences: Lowers FA mobility
changes Tm of phase transition
Lowers membrane permeability for small molecules
Supports domain organization
Asymmetrical distribution of lipids
e.g. plasma membrane
Consequences:
Specific interactions
Signal transduction
Electric contribution to membrane potential
Biological membranes plasma membrane
PLCs
PLDs
Inositol and phosphatidylinositol metabolism
Generation of novel membrane binding sites
Generation of phosphatidic acid
Change in membrane potential
Generation of novel membrane binding sites
PLAs Generation of inflammatory mediators
Phospholipid degradation - signal transduction
Signal transducing lipids
Arachidonic acid
Inflammatory response
Prostaglandine
Signal transducing lipids - PLC action
PI(4,5)P2
Signal transducing lipids - PI kinases
Membrane microdomains (rafts)
Membrane microdomains rich in PIP2, cholesterol, sphingolipids Clustering of these microdomains into larger structures - signalling - membrane transport - lipid driven
- protein driven
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Model membranes
Giant unilamellar vesicles (GUV) – 1-100µm lipid composition and curvature chosen to mimick cellular membrane GUV prepared by electroformation between two Indium-tinoxide (ITO) covered slides 1h, T > Tm, lipid , 10Hz, rectangular wave, 1V (peak to peak)
POPC/DOPC/POPS/Chol/PIP2 (38.4:19.2:20:19.4:3)
Intercalating dyes showing a preference for Ld and Lo phases
DSPC/DOPC/Chol/NBD-DSPE (27:49.9:23:0.1)
GUV
Spontaneous lipid segregation Lo and Ld domains
Visualizing cholesterol – Model membranes
Alexa 594 – Cholesterol analogue
NBD-DSPE
Anna Livia Matos
PI(4,5)P2
PI(3,4,5)P3
Phosphoinositide segregation in cellular polarity
Membrane homeostasis Protein/membrane transport in eukaryontic cells
Principles of vesicle mediated transport
Vesicle tethering and transport
Membrane traffic along the secretory pathway
Membrane traffic along the secretory pathway
Membrane traffic along the endocytic pathway
Distribution of phosphoinositides among endocytic compartments
Domain organization in the endocytic pathway