Functional and structural characterization of the zebrafish Na+-sulfate cotransporter 1 (NaS1) cDNA and gene (slc13a1)

Sulfate plays an essential role during growth, development and cellular metabolism. In this study, we characterized the function and structure of the zebrafish (Danio rerio) Na+-sulfate cotransporter 1 (NaS1) cDNA and gene (slc13a1). Zebrafish NaS1 encodes a protein of 583 amino acids with 13 putative transmembrane domains. Expression of zebrafish NaS1 protein in Xenopus oocytes led to Na+-sulfate cotransport, which was significantly inhibited by thiosulfate, selenate, molybdate, and tungstate. Zebrafish NaS1 transport kinetics were: V(max) = 1,731.670 +/- 92.853 pmol sulfate/oocyte.hour and K(m) = 1.414 +/- 0.275 mM for sulfate and V(max) = 307.016 +/- 32.992 pmol sulfate/oocyte x hour, K(m) = 24.582 +/- 4.547 mM and n (Hill coefficient) = 1.624 +/- 0.354 for sodium. Zebrafish NaS1 mRNA is developmentally expressed in embryos from day 1 postfertilization and in the intestine, kidney, brain, and eye of adult zebrafish. The zebrafish NaS1 gene slc13a1 contains 15 exons spanning 8,716 bp. Characterization of the zebrafish NaS1 contributes to a greater understanding of sulfate transporters in a well-defined genetic model and will allow the elucidation of evolutionary and functional relationships among vertebrate sulfate transporters