Figure 6.

Analysis of Na⁺ and K⁺ binding sites of Na⁺/K⁺-ATPase (Nka) α1, Nkaα2 and Nkaα3 from the gills of Himantura signifer. A multiple amino acid sequence alignment of a region of Nkaα1, Nkaα2, and Nkaα3 from the gills of H. signifer, with (A) Nkaα1a (JN180940) and Nkaα1b (JN180941) from the gills of Anabas testudineus, (B) Nkaα1a (NP_001117933) and Nkaα1b (NP_001117932.1) from the gills of Oncoryhnchus mykiss, and (C) Nkaα1 (AAD11455.2) and Nkaα3 (Genbank: AAF75108.) from the gills of Oreochromis mossambicus. Identical amino acid residues are indicated by shaded residues. Vertical boxes represent coordinating residues for Na⁺ or K⁺ binding. For (A), an asterisk indicates the amino acid residue that is different from Nkaα1a and Nkaα1b. For (B), an asterisk indicates the amino acid residue that is similar to Nkaα1b but different from Nkaα1a. For (C), an asterisk indicates the amino acid residue that is similar to Nkaα1 and Nkaα3.