Manual verification of residue conservation at the active site in both human and yeast orthologs. This is the reciprocal best BLAST hits alignment using yeast protein P05373, Delta-aminolevulinic acid dehydratase for S. cerevisiae, as the query searching against the entire human proteome. The only human hit is P13716, also delta-aminolevulinic acid for H. sapiens. From genbank annotations, we know the active site should occur at position 221 in the human sequence, corresponding to position 232 in the yeast sequence. Here we see conservation not only among the active site residues, but also in the surrounding region, which can also be important in facilitating active site binding.