<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Conde, Artur</style></author><author><style face="normal" font="default" size="100%">Diallinas, George</style></author><author><style face="normal" font="default" size="100%">Chaumont, Fran{\c c}ois</style></author><author><style face="normal" font="default" size="100%">Chaves, Manuela</style></author><author><style face="normal" font="default" size="100%">Gerós, Hernâni</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Transporters, channels, or simple diffusion? Dogmas, atypical roles and complexity in transport systems.</style></title><secondary-title><style face="normal" font="default" size="100%">Int J Biochem Cell Biol</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Active</style></keyword><keyword><style  face="normal" font="default" size="100%">Animals</style></keyword><keyword><style  face="normal" font="default" size="100%">Aquaporins</style></keyword><keyword><style  face="normal" font="default" size="100%">Biological Transport</style></keyword><keyword><style  face="normal" font="default" size="100%">Endocytosis</style></keyword><keyword><style  face="normal" font="default" size="100%">Glucose</style></keyword><keyword><style  face="normal" font="default" size="100%">Humans</style></keyword><keyword><style  face="normal" font="default" size="100%">Ion Channels</style></keyword><keyword><style  face="normal" font="default" size="100%">Monosaccharide Transport Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Post-Translational</style></keyword><keyword><style  face="normal" font="default" size="100%">Protein Processing</style></keyword><keyword><style  face="normal" font="default" size="100%">Saccharomyces cerevisiae</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2010</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2010 Jun</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">42</style></volume><pages><style face="normal" font="default" size="100%">857-68</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The recent breakthrough discoveries of transport systems assigned with atypical functions provide evidence for complexity in membrane transport biochemistry. Some channels are far from being simple pores creating hydrophilic passages for solutes and can, unexpectedly, act as enzymes, or mediate high-affinity uptake, and some transporters are surprisingly able to function as sensors, channels or even enzymes. Furthermore, numerous transport studies have demonstrated complex multiphasic uptake kinetics for organic and mineral nutrients. The biphasic kinetics of glucose uptake in Saccharomyces cerevisiae, a result of several genetically distinct uptake systems operating simultaneously, is a classical example that is a subject of continuous debate. In contrast, some transporters display biphasic kinetics, being bona fidae dual-affinity transporters, their kinetic properties often modulated by post-translational regulation. Also, aquaporins have recently been reported to exhibit diverse transport properties and can behave as highly adapted, multifunctional channels, transporting solutes such as CO(2), hydrogen peroxide, urea, ammonia, glycerol, polyols, carbamides, purines and pyrimidines, metalloids, glycine, and lactic acid, rather than being simple water pores. The present review provides an overview on some atypical functions displayed by transporter proteins and discusses how this novel knowledge on cellular uptake systems may be related to complex multiphasic uptake kinetics often seen in a wide variety of living organisms and the intriguing diffusive uptake of sugars and other solutes.</style></abstract></record></records></xml>