Gt. Berry et al., THE HUMAN OSMOREGULATORY NA+ MYO-INOSITOL COTRANSPORTER GENE (SLC5A3)- MOLECULAR-CLONING AND LOCALIZATION TO CHROMOSOME-21/, Genomics, 25(2), 1995, pp. 507-513
A human Na+/myo-inositol cotransporter (SLC5A3) gene was cloned; seque
ncing revealed a single intron-free open reading frame of 2157 nucleot
ides. Containing 718 amino acid residues, the predicted protein is hig
hly homologous to the product of the canine osmoregulatory SLC5A3 gene
. The SLC5A3 protein is number 3 of the solute carrier family 5 and wa
s previously designated SMIT. Using fluorescence in situ hybridization
, the human SLC5A3 gene was localized to band q22 on chromosome 21. Ma
ny tissues including brain demonstrate gene expression. The inability
of a trisomic 21 cell to downregulate expression of three copies of th
is osmoregulatory gene could result in increased flux of both myo-inos
itol and Na+ across the plasma membrane. The potential consequences in
clude perturbations in the cell membrane potential and tissue osmolyte
levels. The SLC5A3 gene may play a role in the pathogenesis of Down s
yndrome. (C) 1995 Academic Press, Inc.