title: Translocation of the ABC transporter ABCD4 from the endoplasmic reticulum to lysosomes requires the escort protein LMBD1.
abstract: We previously demonstrated that ABCD4 does not localize to peroxisomes but rather, the endoplasmic reticulum (ER), because it lacks the NH2-terminal hydrophilic region required for peroxisomal targeting. It was recently reported that mutations in ABCD4 result in a failure to release vitamin B12 from lysosomes. A similar phenotype is caused by mutations in LMBRD1, which encodes the lysosomal membrane protein LMBD1. These findings suggested to us that ABCD4 translocated from the ER to lysosomes in association with LMBD1. In this report, it is demonstrated that ABCD4 interacts with LMBD1 and then localizes to lysosomes, and this translocation depends on the lysosomal targeting ability of LMBD1. Furthermore, endogenous ABCD4 was localized to both lysosomes and the ER, and its lysosomal localization was disturbed by knockout of LMBRD1. To the best of our knowledge, this is the first report demonstrating that the subcellular localization of the ABC transporter is determined by its association with an adaptor protein.
authors.affiliation: Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Kawaguchi
authors.affiliation: Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Okamoto
authors.affiliation: Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Morita
authors.affiliation: Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Imanaka
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006801:Humans; D008247:Lysosomes / Q000378:metabolism*; D009154:Mutation; D029543:Nucleocytoplasmic Transport Proteins / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: C489273:ABCD4 protein, human; D018528:ATP-Binding Cassette Transporters; C502888:LMBRD1 protein, human; D029543:Nucleocytoplasmic Transport Proteins