Molecular cloning, mapping, and functional analysis of the bovine sulfate transporter SLC26a2 gene

Sulfate is one of the most important macronutrients in cells and the major sulfur source in many organisms as well as one of the most abundant anions in the serum. As sulfate is a hydrophilic anion, movement across the lipid bilayer is mediated by transporters that regulate efflux and influx. Here, we report the molecular cloning, mapping, and functional analysis of the bovine solute carrier/sulfate transporter SLC26a2 gene, the first member of this family to be cloned in cattle. A recombinant phage library was screened, and single phages harbouring the SLC26a2 gene was isolated and sequenced. A fragment of 6295 base pairs (bp) of the bovine SLC26a2 gene harbouring exon 2 and exon 3 was used for further analysis. Similar to the human, ovine, mouse, and rat SLC26a2 gene, the bovine ortholog consists of two coding exons. The open reading frame harbours 2202 nucleotides (nt), coding for a protein of 734 amino acids with a calculated molecular weight of 81.5 kilodaltons (kDa) and a statistical isoelectric point (pI) of 8.77. The bovine SLC26a2 gene was mapped to chromosome 7q23-q24 (BTA 7q23-q24) by fluorescence in situ hybridisation (FISH) analysis. Two point mutations were identified comparing the DNAs of 300 Holstein Frisian cattle, one of them resulting in an isoleucine to serine amino acid exchange at position 520. The Ile520Ser exchange influences the sulfate uptake as measured in primary fibroblasts isolated from testis and in immortalized fibroblastoid bovine cell lines.