FUNCTION AND DYSFUNCTION OF RENAL TRANSPORT MOLECULES - LESSONS FROM ELECTROPHYSIOLOGY

The availability of cloned transport molecules achieved by efforts in expression cloning has allowed their electrophysiological analysis in the Xenopus oocyte expression system. We describe the electrogenic upt ake of various substrates by their corresponding transport molecules o riginally expressed in brush border membranes of proximal tubules. The functional properties of the following transport molecules are discus sed: the sodium-coupled glucose transporter, the sodium-coupled phosph ate transporter, the sodium-coupled sulfate transporter and the sodium -independent transporter of neutral and dibasic amino acids. Additiona lly, functional consequences of naturally occurring disease-causing mu tations in some of these transport molecules are described.