Identification and Characterization of AtSTP14, a Novel Galactose Transporter from Arabidopsis

Abstract

AtSTP14, a new Arabidopsis sugar transporter, was identified and characterized on the molecular and physiological level. Reverse transcriptase-PCR analyses and reporter plants demonstrate high AtSTP14 expression levels in the seed endosperm and in cotyledons, as well as in green leaves. Thus, unlike previously characterized monosaccharide transporters, AtSTP14 is expressed in both source and sink tissues and represents the first monosaccharide transporter in the female gametophyte. Heterologous expression in yeast revealed that AtSTP14 does not transport glucose or fructose, but is the first plant transporter specific for galactose. Interestingly, AtSTP14 expression is regulated by factors which also induce cell wall degradation such as extended dark periods or changes in the sugar level, i.e. AtSTP14 is induced 3-fold by 24 h darkness and repressed 3-fold by 2% glucose and 2% sucrose. Two independent Atstp14 mutant lines were identified, but no effect on seed development or other differences during growth under normal conditions could be observed. A putative role for AtSTP14 in the recycling of cell wall-derived galactose during different developmental processes is discussed.

Polar localization of a symbiosis-specific phosphate transporter is mediated by a transient reorientation of secretion

“…The transporters included an M. truncatula monosaccharide transporter (Medtr8g102860.1), referred to herein as "MtSTP," that shares homology with the Arabidopsis galactose transporter AtSTP14, and an M. truncatula polyol transporter (TC183926), herein referred to as "MtPLT," that shares homology with Arabidopsis AtPLT5. Both Arabidopsis AtSTP14 and AtPLT5 have demonstrated plasma membrane localization (23,24). MtSTP and MtPLT are expressed in roots but are not differentially expressed during AM symbiosis (Medicago Gene Expression Atlas, http://mtgea.noble.org/v2/).…”

Functional characterization and expression analysis of cucumber (Cucumis sativus L.) hexose transporters, involving carbohydrate partitioning and phloem unloading in sink tissues

“…2A). This means CsHT4 is the second galactose-specific hexose transporter to be found in plants (along with AtSTP14 in Arabidopsis) [42]. Expression of CsHT3 in yeast was found to rescue growth on glucose, galactose and mannose ( Fig.…”

A Novel Arabidopsis Vacuolar Glucose Exporter Is Involved in Cellular Sugar Homeostasis and Affects the Composition of Seed Storage Compounds

“…To analyze the effect of darkness and external sugars on AtERDL6 expression, plants were treated as described (Poschet et al, 2010). For heat stress experiments, plants were wrapped in aluminum foil to prevent dehydration and incubated for 6 h at 37°C (stress) or 23°C (control) in an incubator (Binder).…”