Chapter 11: Biological Membranes and Transport
Membranes are much more than just phospholipid
Lipid aggregates
Biological membrane composition
Membrane integral proteins
Computer algorithms are fairly descent at predicting the TM regions within membrane integral protein sequences
Membrane integral proteins
Fluid mosaic model
Fluid mosaic model
Biological transport via vesicle-membrane fusion
Kinetics vs. thermodynamics of transport
Ionophore = chemistry’s Trojan horse.
Diffusion = high to low concentration!
Other types of biological transport
The 2003 Nobel Prize in Chemistry“for discoveries concerning channels in cell membranes”
The potassium channel is an ingenious solution to selectively allowing for potassium, but not sodium
transport
7TMs = GPCRs
Beta-barrel proteins
Three general classes of transport systems
The neurotransmitter/sodium symporter protein family
Yamashita et al., Nature 437, 215-223, 2005.
Phylogenomics of the NSS protein family
Livesay et al., BMC Bioinformatics 8, 397, 2007.
outward open -> occluded -> inward openThis scheme is fairly common
Model of glucose transport into erythrocytes by GluT
Active transport uses ATP hydrolysisto go against the concentration gradient
Oxidative phosphorylation synthesizes ATP, which is driven by the flux of H+ with the concentration gradient
ATPase
The ATP-binding cassette (ABC) transporters and the bacterial periplasmic binding proteins (bPBPs)
bPBP
ATP-binding domains
Transmembrane domains
Substrate
-- Extracellular --
-- Periplasm --
-- Cytosol --bPBP
