The deduced protein, called GLUT11, has 496 amino acids and contains 12 transmembrane domains, all motifs essential for sugar-transport activity, and an N-glycosylation site in loop 1. GLUT11 shares 41.7% identity with GLUT5 (SLC2A5). Western blot analysis detected a 45-kD band in plasma membrane and microsomal fractions from both human heart atrium and ventricle. Northern blot analysis detected a major transcript of 7.2 kb and a minor transcript of 3.6 kb expressed only in heart and skeletal muscle.several GLUT11 splice variants that differed in the utilization or splicing of exons 1a, 1b, and 1c, exon skipping, and utilization of different 3-prime termination sites. The exon 1 variants encode proteins of 496, 503, and 499 amino acids, respectively, that differ in their N-terminal sequence. Northern blot analysis detected tissue-specific expression of the splice variants.