Published Online: 15 SEP 2006
Copyright © 2006 Wiley-VCH Verlag GmbH & Co. KGaA. All rights reserved.
Reviews in Cell Biology and Molecular Medicine
How to Cite
Engvall, C. and Lundahl, P. 2006. Membrane Transport. Reviews in Cell Biology and Molecular Medicine. .
- Published Online: 15 SEP 2006
Small hydrophobic or amphiphilic solutes, such as oxygen or drugs, partition into the lipid bilayer of a cell membrane, diffuse within it, and partition out from it. More polar molecules, for example, glucose, require the help of a membrane protein to traverse the membrane. Porins contain pores of passage, whereas facilitative transporters change conformation to let the substrate through the membrane. Ion channels allow regulated passage of anions or cations. These modes of passive transport are thermally driven toward lower substrate concentration. Active transport proteins concentrate a solute by the use of adenosine triphosphate (ATP) hydrolysis or by means of an ion gradient whereby ions passing through the transporter drive the uphill transport of the substrate. Xenobiotics are expelled from cells by active transporters, for example, P-glycoprotein. Endo- or exocytosis transports compounds across the cell membrane in vesicles budding off from or fusing with the membranes, respectively. Partitioning and transport are analyzed with cells or cell models.
- Amphiphilic Molecule;
- Cell Membrane or Plasma Membrane;
- Hydrophilic Molecule or Atom;
- Hydrophobic Molecule or Atom;
- Membrane Protein;
- Permeability (cm3 s−1) of a Membrane for a Solute;
- Phospholipid Bilayer;
- Phospholipid Molecule;