Regulation of Plasma Membrane Transport

Starting from the earliest studies on mammalian plasma membrane transport, it has become apparent that transport activities, such as enzyme activities, are subject to both short- and long-term regulation. In the past few years, the cloning and sequencing of cDNA for various transport proteins has allowed the exploration of the mechanisms of transport regulation in greater molecular detail. This chapter covers the study of the regulation of transport from the original kinetic experiments to the most recent work using transgenic animals. It also presents a description of the major factors through which the activity of transporters can be modulated. General principles are described in terms of regulation of activity due to changes in transport-driving force, modifications of endogenous transporters, or increase in the number of transporter molecules in the membrane. For each category, selected examples have been considered in detail. As far as possible, the physiological significance of these changes is also discussed. Finally, the chapter reviews the role of disorders of transport regulation in two pathological conditions of wide interest.