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Updated: Aug 29, 2026

Demonstration of Heterologous Complexes formed by Golgi-Resident Type III Membrane Proteins using Split Luciferase Complementation Assay
Published on: September 10, 2020
Galectin 9 is the sugar-regulated urate transporter/channel UAT
Michael S Lipkowitz1, Edgar Leal-Pinto, B Eleazar Cohen
1Division of Nephrology, Department of Medicine, Mount Sinai School of Medicine, New York, New York 10029, USA. mike.lipkowitz@mssm.edu
Abstract:
UAT, also designated galectin 9, is a multifunctional protein that can function as a urate channel/transporter, a regulator of thymocyte-epithelial cell interactions, a tumor antigen, an eosinophil chemotactic factor, and a mediator of apoptosis. We review the evidence that UAT is a transmembrane protein that transports urate, describe our molecular model for this protein, and discuss the evidence from epitope tag and lipid bilayer studies that support this model of the transporter. The properties of recombinant UAT are compared with those of urate transport into membrane vesicles derived from proximal tubule cells in rat kidney cortex. In addition, we review channel functions predicted by our molecular model that resulted in the novel finding that the urate channel activity is regulated by sugars and adenosine. Finally, the presence and possible functions of at least 4 isoforms of UAT and a closely related gene hUAT2 are discussed.
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