title: Biochemical characterization of human ZIP13 protein: a homo-dimerized zinc transporter involved in the spondylocheiro dysplastic Ehlers-Danlos syndrome.
abstract: The human SLC39A13 gene encodes ZIP13, a member of the LZT (LIV-1 subfamily of ZIP zinc transporters) family. The ZIP13 protein is important for connective tissue development, and its loss of function is causative for the spondylocheiro dysplastic form of Ehlers-Danlos syndrome. However, this protein has not been characterized in detail. Here we report the first detailed biochemical characterization of the human ZIP13 protein using its ectopic expressed and the purified recombinant protein. Protease accessibility, microscopic, and computational analyses demonstrated that ZIP13 contains eight putative transmembrane domains and a unique hydrophilic region and that it resides with both its N and C termini facing the luminal side on the Golgi. Analyses including cross-linking, immunoprecipitation, Blue Native-PAGE, and size-exclusion chromatography experiments indicated that the ZIP13 protein may form a homo-dimer. We also demonstrated that ZIP13 mediates zinc influx, as assessed by monitoring the expression of the metallothionein gene and by detecting the intracellular zinc level with a zinc indicator, FluoZin-3. Our data indicate that ZIP13 is a homo-dimerized zinc transporter that possesses some domains that are not found in other LZT family members. This is the first biochemical characterization of the physiologically important protein ZIP13 and the demonstration of homo-dimerization for a mammalian ZIP zinc transporter family member. This biochemical characterization of the human ZIP13 protein provides important information for further investigations of its structural characteristics and function.
authors.affiliation: Laboratory for Cytokine Signaling, RIKEN Research Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Bum-Ho
authors.initials: BH
authors.lastname: Bin
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Fukada
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Hosaka
authors.forename: Satoru
authors.initials: S
authors.lastname: Yamasaki
authors.forename: Wakana
authors.initials: W
authors.lastname: Ohashi
authors.forename: Shintaro
authors.initials: S
authors.lastname: Hojyo
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Miyai
authors.forename: Keigo
authors.initials: K
authors.lastname: Nishida
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Yokoyama
authors.forename: Toshio
authors.initials: T
authors.lastname: Hirano
mesh_terms: D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004535:Ehlers-Danlos Syndrome / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D017136:Ion Transport / Q000235:genetics; D011083:Polycyclic Compounds / Q000737:chemistry; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D015032:Zinc / Q000737:chemistry / Q000378:metabolism*
chemical_list: D027682:Cation Transport Proteins; C451182:FluoZin-3; D011083:Polycyclic Compounds; D011994:Recombinant Proteins; C521172:SLC39A13 protein, human; D015032:Zinc