Membrane Transport

Not many years ago, problems of membranes and transport attracted the attention of but a few dozen enthusiasts, mainly physiolo­ gists who recognize~ the significance of membranes for the stabilization of the general steady state of organisms. The first symposium organ­ ized some fifteen years ago could boast of the attendance of perhaps fifty scientists (the remaining fifty were not yet sure that membranes was the topic of their choice), ranging in specialization from physical chemistry to bacterial genetics, who clairvoyantly decided to study what now has become the number one subject at most congresses of biophysics, physiology, and even biochemistry and microbiology. As is the case with many rapidly developing fields, the interest in membranes and transport seems to be growing out of bounds and the whole field of membra no logy, interdisciplinary as it is, has penetrated into the realms of a number of branches of physics, chemistry, and biology. Its subject is primarily biological and, although much has been done in the world to increase the "exactness" of biology over the past thirty years, one cannot strive for a rigorous mathematical description of biological phenomena since, as M. H.

Contenu

1. Introduction (K. J.).- 1.1. Important events in the history of membranology.- 1.2. Evolution and transport.- 1.3. Transport in space and time.- 2. Membranes (A. K.).- 2.1. Surfaces and interfaces.- 2.2. Chemical composition.- 2.2.1. Lipids.- 2.2.1.1. Chemistry.- 2.2.1.2. Distribution.- 2.2.1.3. Fatty acids.- 2.2.1.4. Solubilization.- 2.2.2. Proteins.- 2.2.2.1. Types and occurrence.- 2.2.2.2. Solubilization.- 2.2.3. Carbohydrates.- 2.3. Structure of membranes.- 2.3.1. Physico-chemical techniques.- 2.3.1.1. X-ray diffraction.- 2.3.1.2. Infrared spectroscopy.- 2.3.1.3. Ultraviolet spectroscopy.- 2.3.1.3.1. Absorption spectra.- 2.3.1.3.2. Optical rotatory dispersion.- 2.3.1.3.3. Circular dichroism.- 2.3.1.4. Nuclear magnetic resonance.- 2.3.1.5. Electron spin resonance.- 2.3.1.6. Fluorescence.- 2.3.1.7. Calorimetry and related techniques.- 2.3.1.8. Other techniques.- 2.3.2. Organization of lipids.- 2.3.2.1. Biological membranes.- 2.3.2.2. Artificial membranes.- 2.3.3. Organization of proteins.- 2.3.4. Lipid-protein interactions and membrane structure.- 2.4. Assembly of membranes.- 2.5. Electron'microscopy.- 2.6. Isolation of membranes.- 2.7. Morphology and function of different biological membranes.- 2.7.1. Plasma membrane.- 2.7.1.1. Morphology.- 2.7.1.2. Functional properties.- 2.7.1.2.1. Antigenicity.- 2.7.1.2.2. Enzyme content.- 2.7.1.2.3. Cell walls.- 2.7.1.2.4. Binding and receptor properties.- 2.7.2. Mitochondrion.- 2.7.3. Chloroplast.- 2.7.4. Mesosome.- 2.7.5. Endoplasmic reticulum.- 2.7.6. Golgi apparatus.- 2.7.7. Lysosome.- 2.7.8. Tonoplast.- 2.7.9. Nucleus.- 2.7.10. Other membranes.- Synopsis.- 3. Thermodynamics of transport (K. J.).- 3.1. Thermodynamic equilibrium, passive and active transport processes.- 3.2. Thermodynamics of the steady state.- 3.3. Network thermodynamics.- Synopsis.- 4. Transport of nonelectrolytes (A. K.).- 4.1. Principles of diffusion (K. J.).- 4.2. Diffusion across membranes (A. K. + K. J.).- 4.3. Kinetics of mediated transport.- 4.3.1. Mediated or facilitated diffusion.- 4.3.1.1. Steady-state approach.- 4.3.1.2. Equilibrium approach.- 4.3.1.3. Two-site carrier.- 4.3.2. Primary active transport.- 4.3.2.1. Kinetics.- 4.3.2.2. Combined systems.- 4.3.2.3. Energetics.- 4.3.3. Coupled transport.- 4.4. Chemical nature of nonelectrolyte transport systems.- 4.4.1. Group-translocation systems.- 4.4.2. Oxidoreductive systems.- 4.4.3. Binding proteins.- 4.5. Distribution and role of nonelectrolyte transport.- Synopsis.- 5. Transport of ions (K. J.).- 5.1. Equilibria of ions.- 5.1.1. A simple membrane equilibrium and membrane potentials.- 5.1.2. Gibbs-Donnan equilibrium.- 5.1.3. Diffuse electrical double layer.- 5.2. Electrodiffusion and membrane potentials.- 5.2.1. Introduction.- 5.2.2. The electrodiffusion equation-general considerations.- 5.2.3. Schlögl's (1964) derivation of the general differential equation of electrodiffusion.- 5.2.4. Henderson's equation-potential difference across a continuous layer with constant concentration gradients of individual ions.- 5.2.5. Planck's procedure-potential difference across a microscopically electroneutral continuous layer.- 5.2.6. Goldman's procedure-potential difference across a continuous layer with constant field.- 5.2.7. Constant-field equation for potential difference across the whole membrane.- 5.2.8. Constant-field equation for steady-state membrane potential in the presence of an electrogenic sodium pump.- 5.2.9. The Hodgkin-Horowicz equation.- 5.3. Chemical nature of ion-translocating systems (A. K.).- 5.3.1. Na, K-Adenosinetriphosphatase.- 5.3.2. Ca-Adenosinetriphosphatase.- 5.3.3. Other adenosinetriphosphatases.- 5.3.4. Ion-binding proteins.- 5.3.5. Transport of ferric ions.- 5.3.6. Ionophores.- 5.4 Distribution and role of ion transport.- Synopsis.- 6. Transport of water (K. J.).- 6.1. Steady-state thermodynamics of water permeation.- 6.2. The state of water in cells.- Synopsis.- 7. Transport by special mechanisms (A. K.).- 7.1. Oligopeptide permeases.- 7.2. Pinocytosis.- 7.3. Uptake of nucleic acids and special proteins.- Synopsis.- References.