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

Abstract

A cDNA encoding the β-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 β-subunit of Anemia should provide information about the functional significance of this protein.