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Updated: Aug 7, 2026

Detection of Detergent-sensitive Interactions Between Membrane Proteins
Published on: March 7, 2018
RS1 (RSC1A1) regulates the exocytotic pathway of Na+-D-glucose cotransporter SGLT1
Maike Veyhl1, Thorsten Keller, Valentin Gorboulev
1Institut für Anatomie und Zellbiologie der Universität Würzburg, Koellikerstr. 6, 97070 Würzburg, Germany.
Abstract:
The product of gene RSC1A1, named RS1, participates in transcriptional and posttranscriptional regulation of the sodium-d-glucose cotransporter SGLT1. Using coexpression in oocytes of Xenopus laevis, posttranscriptional inhibition of human SGLT1 (hSGLT1) and some other transporters by human RS1 (hRS1) was demonstrated previously. In the present study, histidine-tagged hRS1 was expressed in oocytes or Sf9 cells and purified using nickel(II)-charged nitrilotriacetic acid-agarose. hRS1 protein was injected into oocytes expressing hSGLT1 or the human organic cation transporter hOCT2, and the effect on hSGLT1-mediated uptake of methyl-alpha-D-[14C]glucopyranoside ([14C]AMG) or hOCT2-mediated uptake of [14C]tetraethylammonium ([14C]TEA) was measured. Within 30 min after the injection of hRS1 protein, hSGLT1-expressed AMG uptake or hOCT2-expressed TEA uptake was inhibited by approximately 50%. Inhibition of AMG uptake was decreased when a dominant negative mutant of dynamin I was coexpressed and increased after stimulation of PKC. Inhibition remained unaltered when endocytosis was inhibited by chlorpromazine, imipramine, or filipin but was prevented when exocytosis was inhibited by botulinum toxin B or when the release of vesicles from the TGN and endosomes was inhibited by brefeldin A. Inhibition of hSGLT1-mediated AMG uptake and hOCT2-mediated TEA uptake by hRS1 protein were decreased at an enhanced intracellular AMG concentration. The data suggest that hRS1 protein exhibits glucose-dependent, short-term inhibition of hSGLT1 and hOCT2 by inhibiting the release of vesicles from the trans-Golgi network.
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