Analysis of the rainbow trout solute carrier 11 family reveals iron import < or = pH 7.4 and a functional isoform lacking transmembrane domains 11 and 12

A Xenopus oocyte heterologous expression system was used to characterise iron transport properties of two members of the solute carrier 11 (slc11) protein family isolated from rainbow trout gills. One cDNA clone differed from the trout Slc11alpha containing an additional 52bp in the exon between transmembrane domains (TM) 10 and 11. The 52bp contained a stop codon, resulting in a novel isoform lacking the last two TM (termed slc11gamma). Slc11gamma and another isoform slc11beta, import Fe(2+) at external pHs < or = to 7.4. Trout slc11beta Fe(2+) import was more sensitive to inhibition by divalent metals. The novel vertebrate slc11gamma isoform functions without TM11 and 12.