Sequence clustering and conserved regions of UbiA superfamily prenyltransferases. (A) Homology clustering. The representative proteins used in PSI-BLAST search are indicated (prefix: Hs, homo sapiens; Ec, Escherichia coli; At, Arabidopsis thaliana; Tb, Mycobacterium tuberculosis; Hv, Hordeum vulgare; Mj, Methanocaldococcus jannaschii), and their positions (large spheres) are shown within each groups (small dots). However, a cluster cannot be generated for the Af homolog (yellowgreen dots) due to its low homology to other proteins. (B) Alignment of conserved sequence motifs. The conserved Asp residues are colored in red, and other conserved residues in blue.