engleski

The expression of renal transporters in oocytes of Xenopus

Genes encoding diverse transport proteins from the rat, rabbit or human kidney cortex have been recently cloned. There are about 14 transport proteins the most responsible for proximal tubular reabsorption of organic and inorganic substances as a Na+-dependent or Na~-independent cotransporters. It is possible to induce expression of these membrane proteins in Xenopus oocytes which have ability to synthesise exogenous proteins inside 1-8 days when they were injected with cloned cRNA. Using electrophysiological study it is possible to determine the general properties of these transporters expressed in oocytes and to study their regulation (a structure-function relationships). The advantage of using oocytes is also their cell size (up to 1.3 mm in diameter) which allows penetration with two microelectrodes at the same time and voltage and current clamp technique was performed. Mutations occurred in the transporter gene can cause some genetic disorders and because of defective membrane transporters of the renal tubule could be manifested as inherited disease. Mutant transporter gene which causes disease is possible to clone and functional studies using the oocyte system can also be performed. Observed differences in functional expression of wild type and its naturally occurring mutant can be analysed by distinguishing time needed for maximal expression, transporter density in the membrane and its capacity as well as affinity for corresponding substrate.

kidney, cloned transporters, oocyte, electrophysiology

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