Primary Sequence, Tissue Specificity and Expression of the Na+,K+-ATPase α1 Subunit in the European Eel (Anguilla anguilla)

The entire cDNA nucleotide sequence of the Na+,K+-ATPase α 1 isoform was cloned from the gills of the European eel ( Anguilla anguilla ) by a PCR based method. The amino acid sequence translated from the sequence shared 89.4 and 85.6% homology respectively with previously published Na+,K+-ATPase α subunit sequences from elasmobranch ( Torpedo californica ) and teleost ( Catostomus commersoni ) fish. The size of Na+,K+-ATPase α 1 mRNA transcripts in eel tissues was demonstrated to be 3.5 kb, except in the ovary where a 3.7 kb transcript existed. Na+,K+-ATPase α 1 mRNA was present at some level in all tissues investigated with the exception of cardiac and skeletal muscle where no Na+,K+-ATPase α l mRNA was detectable. The level of branchial Na+,K+-ATPase α 1 mRNA increased after the adaptation of freshwater eels to normal or double concentration seawater.