Fig. 3. Phylogenetic relationship of insect sodium/proton exchangers (NHEs). Maximum parsimony analysis of representative NHEs from invertebrates and vertebrates indicates that most cloned vertebrate NHEs belong to the clade that contains mosquito NHE3. The organelle isoforms (NHE6, mitochondria and NHE7, TGN) form a distinct clade, whereas NHE8 isoforms are distantly related to characterized NHE members. The relationship of putative NHE9 and NHE10 to the rest of the family is unclear since it shares closer relationship to bacterial NHEs, which might suggest a possible horizontal transfer. Bootstrap values from 100 replications are given at nodes. Horizontal lines are proportional to the number of changes from the previous node. Accession numbers are given in parentheses. Invertebrate NHEs are shown in color. The original designation of Drosophila NHEs by Giannakou and Dow (2001) is given in parentheses next to their reassigned designations. The tree was rooted with E. coli NHE as outgroup.