Fig. 10. Clustal alignment of CA protein sequences. All characterized human CA isoforms are presented along with predicted GPI-linked CA isoforms from Aedes aegypti, Anopheles gambiae and Drosophila melanogaster. Histidine residues that are required for the essential binding of zinc are shaded in blue. Note that one or more of these histidine residues are missing from the inactive human CA-related proteins VIII, X and XI, while all three histidines are present within the Dipteran sequences. These three species of Dipteran CAs contain a shortened active site region (marked by red dashes) when compared to any of the human (or other mammalian) CA sequences. This difference may provide a potential target for mosquito-specific CA inhibitors. Asterisks, identical residues; dots, conserved residues.