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 3. Conserved sequence found in GDP-sugar transporters. Alignment using the Clustal W program. The pattern contains the GXLNK sequence that binds GDP. The highly conserved sequences are boxed in black while the less conserved ones are boxed in gray.