Expression of Na+,K+-ATPase β subunit isoforms in the European eel (Anguilla anguilla)

Abstract

Reverse transcriptase – polymerase chain reaction experiments utilising degenerate primers were used to demonstrate that the Na+,K+-ATPase β3 but not β2 isoform was present in brain tissue from the European eel (Anguilla anguilla). Two cDNA fragments were cloned and sequenced yielding 445 nucleotides of the Na+,K+-ATPase β3 isoform sequence. The putative amino acid sequence translated from this nucleotide sequence shared 58.0, 50.6 and 50.3% homology with previously published Na+,K+-ATPase “β3-like” isoform sequences from the clawed toad (Xenopus laevis), the chicken (Gallus domesticus) and the toad (Bufo marinus) respectively. The size of the Na+,K+-ATPase β3 mRNA transcript in eel tissues was demonstrated to be 2.4 Kb. Detectable levels of Na+,K+-ATPase β3 mRNA were only found in brain tissue. The tissue specific distribution of the β3 mRNA suggests that it plays little or no direct role in the process of osmoregulation in tissues such as the intestine or gill.