These characteristic features imply that TRET1 in combination with trehalose has high potential for basic and practical applications in vivo. Furthermore, TRET1 was found to function in mammalian cells, suggesting that it confers trehalose permeability on cells, including those of vertebrates as well as insects. The extraordinarily high values for apparent K m (≥100 mM) and V max (≥500 pmol/min per oocyte) for trehalose both indicate that TRET1 is a high-capacity transporter of trehalose. These results indicate that TRET1 is a trehalose-specific facilitated transporter and that the direction of transport is reversible depending on the concentration gradient of trehalose. Functional expression of TRET1 in Xenopus oocytes showed that transport activity was stereochemically specific for trehalose and independent of extracellular pH (between 4.0 and 9.0) and electrochemical membrane potential. Expression was predominant in the fat body and occurred concomitantly with the accumulation of trehalose, indicating that TRET1 is involved in transporting trehalose synthesized in the fat body into the hemolymph. Tret1 expression was induced by either desiccation or salinity stress. Tret1 cDNA encodes a 504-aa protein with 12 predicted transmembrane structures. ![]() In this study, we isolated and characterized the functions of a facilitated trehalose transporter from an anhydrobiotic insect, Polypedilum vanderplanki. ![]() A major obstacle to application is that cellular membranes are impermeable to trehalose. Trehalose is potentially a useful cryo- or anhydroprotectant molecule for cells and biomolecules such as proteins and nucleotides.
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