title: Molecular characterization of zebrafish Oatp1d1 (Slco1d1), a novel organic anion-transporting polypeptide.
abstract: The organic anion-transporting polypeptide (OATP/Oatp) superfamily includes a group of polyspecific transporters that mediate transport of large amphipathic, mostly anionic molecules across cell membranes of eukaryotes. OATPs/Oatps are involved in the disposition and elimination of numerous physiological and foreign compounds. However, in non-mammalian species, the functional properties of Oatps remain unknown. We aimed to elucidate the role of Oatp1d1 in zebrafish to gain insights into the functional and structural evolution of the OATP1/Oatp1 superfamily. We show that diversification of the OATP1/Oatp1 family occurs after the emergence of jawed fish and that the OATP1A/Oatp1a and OATP1B/Oatp1b subfamilies appeared at the root of tetrapods. The Oatp1d subfamily emerged in teleosts and is absent in tetrapods. The zebrafish Oatp1d1 is similar to mammalian OATP1A/Oatp1a and OATP1B/Oatp1b members, with the main physiological role in transport and balance of steroid hormones. Oatp1d1 activity is dependent upon pH gradient, which could indicate bicarbonate exchange as a mode of transport. Our analysis of evolutionary conservation and structural properties revealed that (i) His-79 in intracellular loop 3 is conserved within OATP1/Oatp1 family and is crucial for the transport activity; (ii) N-glycosylation impacts membrane targeting and is conserved within the OATP1/Oatp1 family with Asn-122, Asn-133, Asn-499, and Asn-512 residues involved; (iii) the evolutionarily conserved cholesterol recognition interaction amino acid consensus motif is important for membrane localization; and (iv) Oatp1d1 is present in dimeric and possibly oligomeric form in the cell membrane. In conclusion, we describe the first detailed characterization of a new Oatp transporter in zebrafish, offering important insights into the functional evolution of the OATP1/Oatp1 family and the physiological role of Oatp1d1.
authors.affiliation: Laboratory for Molecular Ecotoxicology, Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, 10 000 Zagreb, Croatia.
authors.forename: Marta
authors.initials: M
authors.lastname: Popovic
authors.affiliation: Laboratory for Molecular Ecotoxicology, Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, 10 000 Zagreb, Croatia.
authors.forename: Roko
authors.initials: R
authors.lastname: Zaja
authors.affiliation: School of Life Sciences, University of Applied Sciences Northwestern Switzerland, Gründenstrasse 40, CH-4132 Muttenz, Switzerland; Department of Environmental System Sciences, Swiss Federal Institute of Technology (ETHZ), CH-8092 Zürich, Switzerland.
authors.forename: Karl
authors.initials: K
authors.lastname: Fent
authors.affiliation: Laboratory for Molecular Ecotoxicology, Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, 10 000 Zagreb, Croatia. Electronic address: smital@irb.hr.
authors.forename: Tvrtko
authors.initials: T
authors.lastname: Smital
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D006031:Glycosylation; D012739:Gonadal Steroid Hormones / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D017136:Ion Transport / Q000502:physiology; D027361:Organic Anion Transporters / Q000235:genetics / Q000378:metabolism*; D055503:Protein Multimerization / Q000502:physiology*; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D012739:Gonadal Steroid Hormones; D027361:Organic Anion Transporters; D029961:Zebrafish Proteins
keywords: Cell Metabolism; Membrane Proteins; Membrane Transport; New Slco Transporter in Zebrafish, Molecular Characterization; New Slco Transporter in zebrafish; Organic Anion Channels; Zebrafish