Cladogram of UGPase and related proteins. Plant and animal UGPases form separate clades, related to AGXs and, to a lesser degree, to SPS. There is little or no homology between eukaryotic and prokaryotic UGPases, but the latter share significant homology with the Arabidopsis SuSy family. UGPase-2 is the second divergent UGPase protein in C. elegans and slime mold, whereas UGPases-1 from both organisms fall within the animal UGPase clade. This figure was generated with Clustal-X (v 1.83) alignment and Tree-view (v 1.66).