M. Handford, C. Rodriguez-Furlán and A. Orellana. Nucleotide-sugar transporters: structure, function and roles in vivo. Braz J Med Biol Res 2006; 39: 1149-1158.  

Figure 5. Highly conserved glycine and leucine are located in a putative transmembrane domain. Alignment using Clustal W. Putative transmembrane domains 6 (TMD6) and 7 (TMD7) are highlighted. The highly conserved residues G and L are boxed in black and other conserved residues are boxed in dark gray.