InterPro domain: IPR044778

The family represents plant sugar transport proteins (STPs), also known as hexose transporters, including STP1-STP14 from Arabidopsis and Sugar transport proteins MST1-8 from Oryza sativa subsp. japonica [ 1 ]. They mediate the active uptake of hexoses such as glucose, 3-O-methylglucose, fructose, xylose, mannose, galactose, fucose, 2-deoxyglucose and arabinose, by sugar/hydrogen symport. Several STP family transporters are expressed in a tissue-specific manner, or at specific developmental stages. STP1 is the member with the highest expression level of all members and high expression is detected in photosynthetic tissues, such as leaves and stems, while roots, siliques, and flowers show lower expression levels. It plays a major role in the uptake and response of Arabidopsis seeds and seedlings to sugars [ 2 , 3 ].

1. Molecular cloning, functional characterization and expression analysis of a novel monosaccharide transporter gene OsMST6 from rice (Oryza sativa L.). Planta 228, 525-35
2. Sugar regulation of SUGAR TRANSPORTER PROTEIN 1 (STP1) expression in Arabidopsis thaliana. J Exp Bot 66, 147-59
3. Expression of Arabidopsis sugar transport protein STP13 differentially affects glucose transport activity and basal resistance to Botrytis cinerea. Plant Mol Biol 85, 473-84