IngentaConnect The apical localization of SGLT1 glucose transporter is determine...

Authors: Suzuki T.^{1, 2}; Fujikura K.¹; Koyama H.¹; Matsuzaki T.^{1, 2}; Takahashi Y.²; Takata K.^{1, 2}

Source: European Journal of Cell Biology, Volume 80, Number 12, December 2001 , pp. 765-774(10)

Abstract:

SGLT1, an isoform of Na⁺-dependent glucose cotransporters, is localized at the apical plasma membrane in the epithelial cells of the small intestine and the kidney, where it plays a pivotal role in the absorption and reabsorption of sugars, respectively. To search the domain responsible for the apical localization of SGLT1, we constructed an N-terminal deletion clone series of rat SGLT1 and analyzed the localization of the respective products in Madin-Darby canine kidney (MDCK) cells. The products of N-terminal deletion clones up to the 19th amino acid were localized at the apical plasma membrane, whereas the products of N-terminal 20- and 23-amino-acid deletion clones were localized along the entire plasma membrane. Since single-amino-acid mutations of either D28N or D28G in the N-terminal domain give rise to glucose/galactose malabsorption disease, we examined the localization of these mutants. The products of D28N and D28G clones were localized in the cytoplasm, showing that the aspartic acid-28 may be essential for the delivery of SGLT1 to the plasma membrane. These results suggest that a short amino acid sequence of the N-terminal domain of SGLT1 plays important roles in plasma membrane targeting and specific apical localization of the protein.

Keywords: Cell polarity; MDCK; apical plasma membrane; Na+-dependent cotransporter

Language: English

Document Type: Original article

DOI: 10.1078/0171-9335-00204

Affiliations: 1: Department of Cell Biology, Institute for Molecular and Cellular Regulation, Gunma University, Gunma/Japan 2: Department of Anatomy and Cell Biology, Gunma University School of Medicine, Gunma/Japan

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The apical localization of SGLT1 glucose transporter is determined by the short amino acid sequence in its N-terminal domain