NUCLEOBASE AND NUCLEOSIDE TRANSPORT IN MA MMALIAN-CELLS

Membrane transport of nucleobases and nucleosides has been an actively pursued research field for the past 25 years. Not only are these subs tances of physiological inter eat; derivatives are in clinical use or under investigation for their pharmacological activity against viral a nd neoplastic disease. An understanding of the molecular pharmacology of these substances includes a detailed knowledge of how they reach th eir intracellular targets. Membrane transport systems which have so fa r been found in all cells examined play an important role in this proc ess. Since the transporters are minor membrane components, little is k nown about them on a molecular basis. This review discusses methodolog ical approaches used to measure initial rates of membrane transport an d summarizes current knowledge of the various transport systems which have been characterized with these kinetic methods.