The hexose carrier from Chlorella

Abstract

The cDNA coding for the inducible H⁺/hexose cotransporter of Chlorella kessleri has been cloned and sequenced. It was isolated by differential screening of a cDNA library prepared from glucose-induced cells. The increase in expression of the gene correlates quantitatively with the increase in uptake activity due to induction; it is not expressed in a hexose transport mutant. An open reading frame allows for a membrane protein of 533 amino acids with a relative molecular mass of 57 kDa. This protein is highly homologous to the human and rat glucose transporters catalyzing facilitated diffusion and to the bacterial H⁺/pentose cotransporters. It is not related to the H⁺/lactose cotransporter of E.colli and to the mammalian Na⁺/glucose cotransporter.