title: The structural and functional units of heteromeric amino acid transporters. The heavy subunit rBAT dictates oligomerization of the heteromeric amino acid transporters.
abstract: Heteromeric amino acid transporters are composed of a catalytic light subunit and a heavy subunit linked by a disulfide bridge. We analyzed the structural and functional units of systems b0,+ and xC-, formed by the heterodimers b0,+ AT-rBAT and xCT-4F2hc, respectively. Blue Native gel electrophoresis, cross-linking, and fluorescence resonance energy transfer in vivo indicate that system b0,+ is a heterotetramer [b0,+ AT-rBAT]2, whereas xCT-4F2hc seems not to stably or efficiently oligomerize. However, substitution of the heavy subunit 4F2hc for rBAT was sufficient to form a heterotetrameric [xCT-rBAT]2 structure. The functional expression of concatamers of two light subunits (which differ only in their sensitivity to inactivation by a sulfhydryl reagent) suggests that a single heterodimer is the functional unit of systems b0,+ and xC-.
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Spain.
authors.forename: Esperanza
authors.initials: E
authors.lastname: Fernández
authors.forename: Maite
authors.initials: M
authors.lastname: Jiménez-Vidal
authors.forename: María
authors.initials: M
authors.lastname: Calvo
authors.forename: Antonio
authors.initials: A
authors.lastname: Zorzano
authors.forename: Francesc
authors.initials: F
authors.lastname: Tebar
authors.forename: Manuel
authors.initials: M
authors.lastname: Palacín
authors.forename: Josep
authors.initials: J
authors.lastname: Chillarón
mesh_terms: D026905:Amino Acid Transport Systems / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D019281:Dimerization; D031541:Fluorescence Resonance Energy Transfer; D027282:Fusion Regulatory Protein 1, Heavy Chain / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D009865:Oocytes / Q000166:cytology / Q000502:physiology; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D026905:Amino Acid Transport Systems; D027282:Fusion Regulatory Protein 1, Heavy Chain; D008164:Luminescent Proteins; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins