Book excerpt: An introduction to the principles of membrane transport: How molecules and ions move across the cell membrane by simple diffusion and by making use of specialized membrane components (channels, carriers, and pumps). The text emphasizes the quantitative aspects of such movement and its interpretation in terms of transport kinetics. Molecular studies of channels, carriers, and pumps are described in detail as well as structural principles and the fundamental similarities between the various transporters and their evolutionary interrelationships. The regulation of transporters and their role in health and disease are also considered. - Provides an introduction to the properties of transport proteins: channels, carriers, and pumps - Presents up-to-date information on the structure of transport proteins and on their function and regulation - Includes introductions to transport kinetics and to the cloning of genes that code transport proteins - Furnishes a link between the experimental basis of the subject and theoretical model building