haixu tang school of informatics
DESCRIPTION
Membrane Lipids Are Amphipathic MoleculesTRANSCRIPT
Cell Membrane
Haixu TangSchool of Informatics
Membrane Lipids Are Amphipathic Molecules
hydrophilic and hydrophobic molecules interact differently with water
Packing arrangements of lipid molecules
The spontaneous closure of a phospholipid bilayer
Phospholipid mobility
The other composition of membraneCholesterol and glycolipids
It inhibits possible phase transitions: (1) decreases the permeability of the bilayer to small water-soluble molecules; (2) prevents the hydrocarbon chains from coming together and crystallizing.
Cholesterol
Glycolipid
Four major phospholipids in mammalian plasma membranes
Cell wall
Lipid raft
The asymmetrical distribution of phospholipids and glycolipids
Functions of phospholipids in cell signaling
Membrane proteins
Membrane attachment of Water soluble proteins
Transmembrane polypeptide chain crossing the lipid bilayer
Using hydropathy plots to localize potential -helical membrane-spanning segments
-barrels (occasionally)
Solubilizing membrane proteins with a mild detergent
Two detergent
Reconstituting functional membrane
protein system
Red cell membrane
Preparing red cell ghosts
SDS polyacrylamide-gel electrophoresis pattern of the proteins in the human red
blood cell membrane
Three major ways of proteins association with membranes
• Noncovalently Associated with the Cytosolic Side: Spectrin
• Extends Through the Red Blood Cell Lipid Bilayer as a Single a Helix: Glycophorin
• Multipass Membrane Protein: Band 3 protein
Spectrin: cytoskeleton protein
Spectrin-based cytoskeleton
Glycophorin: single pass membrane proteins
Band 3: Anion Transporter
The polypeptide chain (about 930 amino acids long) is thought to extend across the bilayer 12 times.
Photosynthetic reaction center
The Cell Surface Is Coated with Sugar Residues
Carrier proteins and channel proteins
A typical ion channel
The gating of ion channels
Potassium ion gate
Passive and active transport
Three ways of driving active transport