This invention relates to an isolated nucleic acid fragment encoding a sugar transport protein, more specifically an Arabidopsis-like or Beta-vulgaris-like sugar transport protein. The invention also relates to the construction of a recombinant DNA construct encoding all or a portion of the sugar transport protein, in sense or antisense orientation, wherein expression of the recombinant DNA construct results in production of altered levels of the Arabidopsis-like or Beta-vulgaris-like sugar transport protein in a transformed host cell.