Aquaporins are transmembrane protein channels presented in all life forms from bacteria to human. Currently, there are 13 aquaporins in human which are differentially expressed in various tissues forming either aquaporin channels (transfer water) or aquaglyceroporin channels (transfer water and other solutes). Recently, mutations in human aquaporins have been reported to be associated with various diseases. In this study, full length cDNA sequences of human aquaporins were used to draw the phylogenetic relationship among them and to site the amino acid substitutions especially in the conserved NPA motifs and other conserved residues. The results indicated that, some aquaporins do not maintain the first conserved NPA motif, such as Aqua11 and Aqua12, or the two conserved NPA motifs like Aqua7. Other molecular features of human aquaporins were reported including the length of the N-terminus and the C-terminus and the spacer between the two conserved NPA motifs. The obtained phylogenetic trees using the nucleotide sequence of the coding regions or the amino acid sequences had different topologies. On both phylogenetic trees, the bacterial GlpF aquaglyceroporin did not come at the root of the tree, indicating that it came to existence after human aquaporins, contradicting the evolution theory of Darwin. The results of this study shed light on the possibility of using aquaporin SNPs as diagnostic tool for obesity.
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