Identification of aquaporin 1 in Diplodus sargus

Aquaporin 1 (AQP-1) is the first member of the aquaporin family, which includes seven homologs in teleosts, involved in the selective transport of water, small neutral molecules, and ions. AQPs contain six transmembrane helices, five connecting loops, and the amino and carboxyl ends protrude into the cytoplasm. AQPs are important for osmoregulation in fish gills (independent of salinity), kidneys, and intestine. Here, the nucleotide and amino acid sequences of AQP-1 in Diplodus sargus were characterized, and a phylogenetic tree was built to study its evolution. Results showed that AQP-1 mRNA is 1,325 nucleotides in length, and the deduced protein contains two canonical Asn-Pro-Ala (NPA) consensus motifs and all features for water transport. D. sargus AQP-1 is located in a homophyletic branch with Sparus aurata only, inside of a sub-tree in a paraphyletic position with Centropristis striata and Osmerus mordax. Although the structure of the AQP protein in different species is conserved, results showed that the S. aurata and D. sargus AQP-1 proteins have evolved similarly.