Dataset Information

The Human SLC1A5 (ASCT2) Amino Acid Transporter: From Function to Structure and Role in Cell Biology.

ABSTRACT: SLC1A5, known as ASCT2, is a neutral amino acid transporter belonging to the SLC1 family and localized in the plasma membrane of several body districts. ASCT2 is an acronym standing for Alanine, Serine, Cysteine Transporter 2 even if the preferred substrate is the conditionally essential amino acid glutamine, with cysteine being a modulator and not a substrate. The studies around amino acid transport in cells and tissues began in the '60s by using radiolabeled compounds and competition assays. After identification of murine and human genes, the function of the coded protein has been studied in cell system and in proteoliposomes revealing that this transporter is a Na+ dependent antiporter of neutral amino acids, some of which are only inwardly transported and others are bi-directionally exchanged. The functional asymmetry merged with the kinetic asymmetry in line with the physiological role of amino acid pool harmonization. An intriguing function has been described for ASCT2 that is exploited as a receptor by a group of retroviruses to infect human cells. Interactions with scaffold proteins and post-translational modifications regulate ASCT2 stability, trafficking and transport activity. Two asparagine residues, namely N163 and N212, are the sites of glycosylation that is responsible for the definitive localization into the plasma membrane. ASCT2 expression increases in highly proliferative cells such as inflammatory and stem cells to fulfill the augmented glutamine demand. Interestingly, for the same reason, the expression of ASCT2 is greatly enhanced in many human cancers. This finding has generated interest in its candidacy as a pharmacological target for new anticancer drugs. The recently solved 3D structure of ASCT2 will aid in the rational design of such therapeutic compounds.

SUBMITTER: Scalise M

PROVIDER: S-EPMC6131531 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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The Human SLC1A5 (ASCT2) Amino Acid Transporter: From Function to Structure and Role in Cell Biology.

Scalise Mariafrancesca M Pochini Lorena L Console Lara L Losso Maria A MA Indiveri Cesare C

Frontiers in cell and developmental biology 20180904

SLC1A5, known as ASCT2, is a neutral amino acid transporter belonging to the SLC1 family and localized in the plasma membrane of several body districts. ASCT2 is an acronym standing for Alanine, Serine, Cysteine Transporter 2 even if the preferred substrate is the conditionally essential amino acid glutamine, with cysteine being a modulator and not a substrate. The studies around amino acid transport in cells and tissues began in the '60s by using radiolabeled compounds and competition assays. A ...[more]

PMID: 30234109

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Project description:The human SLC1A5 commonly known as ASCT2 is a sodium-dependent neutral amino acid antiporter involved in transmembrane traffic of glutamine that is exchanged through the cell membrane with smaller amino acids such as serine or threonine. Due to the strong overexpression in human cancers, ASCT2 is widely studied for its relevance to human health. Of special interest are the aspects related to the regulation of its function. The role of cholesterol as a modulator of the transport activity has been studied using a combined strategy of computational and experimental approaches. The effect of cholesterol on the Naex+ -[3H]glutamineex/glutaminein antiport in proteoliposomes has been evaluated by adding cholesteryl hemisuccinate. A strong stimulation of transport activity was observed in the presence of 75 μg cholesteryl hemisuccinate per mg total lipids. The presence of cholesterol did not influence the proteoliposome volume, in a wide range of tested concentration, excluding that the stimulation could be due to effects on the vesicles. cholesteryl hemisuccinate, indeed, improved the incorporation of the protein into the phospholipid bilayer to some extent and increased about three times the Vmax of transport without affecting the Km for glutamine. Docking of cholesterol into the hASCT2 trimer was performed. Six poses were obtained some of which overlapped the hypothetical cholesterol molecules observed in the available 3D structures. Additional poses were docked close to CARC/CRAC motifs (Cholesterol Recognition/interaction Amino acid Consensus sequence). To test the direct binding of cholesterol to the protein, a strategy based on the specific targeting of tryptophan and cysteine residues located in the neighborhood of cholesterol poses was employed. On the one hand, cholesterol binding was impaired by modification of tryptophan residues by the Koshland's reagent. On the other hand, the presence of cholesterol impaired the interaction of thiol reagents with the protein. Altogether, these results confirmed that cholesterol molecules interacted with the protein in correspondence of the poses predicted by the docking analysis.

Dataset Information

The Human SLC1A5 (ASCT2) Amino Acid Transporter: From Function to Structure and Role in Cell Biology.

Publications

The Human SLC1A5 (ASCT2) Amino Acid Transporter: From Function to Structure and Role in Cell Biology.

Similar Datasets

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