Characterization of human glucose transporter (GLUT) 11 (encoded by SLC2A11), a novel sugar-transport facilitator specifically expressed in heart andskeletal muscle

Human GLUT11 (encoded by the solute carrier 2A11 gene, SLC2A11) is a novel sugar transporter which exhibits significant sequence similarity with the m embers of the GLUT family. The amino acid sequence deduced from its cDNAs p redicts 12 putative membrane-spanning helices and all the motifs (sugar-tra nsporter signatures) that have previously been shown to be essential for su gar-transport activity. The closest relative of GLUT11 is the fructose tran sporter GLUT5 (sharing 41.7% amino acid identity with GLUT11). The human GL UT11 gene (SLC2A11) consists of 12 exons and is located on chromosome 22q11 .2. In human tissues, a 7.2 kb transcript of GLUT11 was detected exclusivel y in heart and skeletal muscle. Transfection of COS-7 cells with GLUT11 cDN A significantly increased the glucose-transport activity reconstituted from membrane extracts as well as the specific binding of the sugar-transporter ligand cytochalasin B. In contrast to that of GLUT4, the glucose-transport activity of GLUT11 was markedly inhibited by fructose. It is concluded tha t GLUT11 is a novel, muscle-specific transport facilitator that is a member of the extended GLUT family of sugar/polyol-transport facilitators.