Molecular genetics of Na,K-ATPase

Molecular cloning of the beta-subunit of the Na,K-ATPase in the brine shrimp, Artemia. The cDNA-derived amino acid sequence shows low homology with the beta-subunits of vertebrates except in the single transmembrane and the carboxy-terminal domains

A cDNA encoding the beta-subunit of the Na,K-ATPase of brine shrimp (Artemia) has been cloned. Its nucleotide sequence and predicted amino acid sequence have been determined. The amino acid sequence shows considerable divergence from that of chicken, dog, human, pig, rat, sheep, Torpedo, and Xenopus. This is not entirely unexpected since brine shrimp is a 'fast clock' organism which diverged from the precursor of the vertebrates 0.5-1.0 billion years ago. However, a highly hydrophobic putative transmembrane domain and the carboxy-terminal domain show considerable conservation. The relatively small degree of conservation in the beta-subunit of Artemia should provide information about the functional significance of this protein.

The human Na, K-ATPase alpha 1 gene: characterization of the 5'-flanking region and identification of a restriction fragment length polymorphism

We have determined the sequence of the 5'-flanking region and first three exons of the human Na,K-ATPase alpha 1 gene, ATP1A1. Primer extension and S1 nuclease protection analyses of RNA from human kidney, brain, and skeletal muscle indicate that transcription initiates 273 nucleotides upstream of the translation start site. The promoter region contains a potential TATA box at position -27 relative to the transcription initiation site; however, no CCAAT sequence is observed. The 5'-untranslated and 5'-flanking regions are G + C rich. Five sequence elements exhibiting similarity to binding sites for the transcription factor Sp1 are located within the 5'-flanking region. This region also contains potential binding sites for the transcription factors AP-1, AP-2, AP-3, and NF-1, as well as a site which exhibits perfect identity to an 8-bp sequence element important for calcium induction. A comparison of the 5'-flanking region of the alpha 1 and alpha 2 genes reveals differences in potential transcription factor and hormone receptor binding sites which may be important in mediating the tissue- and developmental stage-specific expression of these genes. We have also identified an intragenic DNA probe which detects a restriction fragment length polymorphism at the alpha 1 locus. This marker should facilitate genetic linkage studies designed to evaluate the role of the sodium pump in human disease.