title: Transporter associated with antigen processing-like (ABCB9) stably expressed in Chinese hamster ovary-K1 cells is sorted to the microdomains of lysosomal membranes.
abstract: The carboxyl terminus of a human ATP-binding cassette (ABC) transporter, transporter associated with antigen processing (TAP)-like (TAPL), was tagged with green fluorescence protein (GFP), and the resulting fusion protein (TAPL-GFP) was stably expressed in Chinese hamster ovary (CHO)-K1 cells. The GFP signal was co-localized with that of LysoTracker but not that of MitoTracker, as visualized under a microscope. TAPL-GFP was co-sedimented with lysosomal marker cathepsin D on Percoll density gradient centrifugation. These results indicated that TAPL is a lysosomal ABC transporter but not a mitochondrial one. It was not solubilized completely with a non-ionic detergent under ice-cold conditions, and was co-sedimented with flotillin-1 on sucrose density gradient centrifugation. A similar result was obtained with high pH-treatment. Furthermore, treatment with methyl-β-cyclodextrin resulted in an altered distribution of TAPL-GFP. These results suggest that TAPL may be localized to the microdomains (lipid rafts) of lysosomal membranes enriched in cholesterol.
authors.affiliation: Department of Molecular Biology, School of Pharmacy, Iwate Medical University, Shiwa-gun, Iwate 028–3694, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Fujimoto
authors.forename: Aya
authors.initials: A
authors.lastname: Kamakura
authors.forename: Yu
authors.initials: Y
authors.lastname: Motohashi
authors.forename: Ayako
authors.initials: A
authors.lastname: Ohashi-Kobayashi
authors.forename: Masatomo
authors.initials: M
authors.lastname: Maeda
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D005786:Gene Expression Regulation / Q000502:physiology; D008247:Lysosomes / Q000378:metabolism*; D021962:Membrane Microdomains / Q000378:metabolism*; D021381:Protein Transport
chemical_list: C412573:ABCB9 protein, human; D018528:ATP-Binding Cassette Transporters