Cystinuria-specific rBAT(R365W) mutation reveals two translocation pathways in the amino acid transporter rBAT-b0,+AT
- PINEDA, Marta Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona Science Park, Barcelona 08028, Spain
- WAGNER, Carsten A. Institute of Physiology, University of Zürich, 8057 Zürich, Switzerland
- BRÖER, Angelika School of Biochemistry and Molecular Biology, Australian National University, Canberra, ACT 0200, Australia
- STEHBERGER, Paul A. Institute of Physiology, University of Tübingen, 72076 Tübingen, Germany
- KALTENBACH, Simone Institute of Physiology, University of Tübingen, 72076 Tübingen, Germany
- GELPÍ, Josep Ll. Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona Science Park, Barcelona 08028, Spain
- MARTÍN del RÍO, Rafael Servicio de Neurobiología, Hospital Ramón y Cajal, Crta de Colmenar Km 7, 28034 Madrid, Spain
- ZORZANO, Antonio Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona Science Park, Barcelona 08028, Spain
- PALACÍN, Manuel Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona Science Park, Barcelona 08028, Spain
- LANG, Florian Institute of Physiology, University of Tübingen, 72076 Tübingen, Germany
- BRÖER, Stefan Institute of Physiology, University of Tübingen, 72076 Tübingen, Germany
Published in:
- Biochemical Journal. - Portland Press Ltd.. - 2004, vol. 377, no. 3, p. 665-674
English
Apical reabsorption of dibasic amino acids and cystine in kidney is mediated by the heteromeric amino acid antiporter rBAT/b0,+AT (system b0,+). Mutations in rBAT cause cystinuria type A, whereas mutations in b0,+AT cause cystinuria type B. b0,+AT is the catalytic subunit, whereas it is believed that rBAT helps the routing of the rBAT/b0,+AT heterodimeric complex to the plasma membrane. In the present study, we have functionally characterized the cystinuria-specific R365W (Arg365→Trp) mutation of human rBAT, which in addition to a trafficking defect, alters functional properties of the b0,+ transporter. In oocytes, where human rBAT interacts with the endogenous b0,+AT subunit to form an active transporter, the rBAT(R365W) mutation caused a defect of arginine efflux without altering arginine influx or apparent affinities for intracellular or extracellular arginine. Transport of lysine or leucine remained unaffected. In HeLa cells, functional expression of rBAT(R365W)/b0,+AT was observed only at the permissive temperature of 33 °C. Under these conditions, the mutated transporter showed 50% reduction of arginine influx and a similar decreased accumulation of dibasic amino acids. Efflux of arginine through the rBAT(R365W)/b0,+AT holotransporter was completely abolished. This supports a two-translocation-pathway model for antiporter b0,+, in which the efflux pathway in the rBAT(R365W)/b0,+AT holotransporter is defective for arginine translocation or dissociation. This is the first direct evidence that mutations in rBAT may modify transport properties of system b0,+.
- Language
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- English
- Open access status
- green
- Identifiers
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- DOI 10.1042/bj20030956
- ISSN 0264-6021
- Persistent URL
- https://folia.unifr.ch/global/documents/23894
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