Molecular cloning of the β‐subunit of the Na,K‐ATPase in the brine shrimp, Artemia

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.

Polymorphism and structure of the gene coding for the α1 subunit of the Artemia franciscana Na/K-ATPase

“…Later studies also led to the isolation of cDNA clones coding for two α subunits, that are 74 % identical at the amino acid level, and one β subunit [14][15][16]. The existence of more than one α subunit gene has also been shown in vertebrates, where three functional genes have been characterized [17].…”

A Na pump with reduced stoichiometry is up-regulated by brine shrimp in extreme salinities

“…The resulting transcriptome contains two β subunit splice variants (β1 and β2). While β1 differs from previously available sequences at a few residues within the extracellular globular domain ( 15 ), β2 has a distinct N terminus ( SI Appendix , Fig. S1 ).…”

“…Our initial attempts to express the published version of Artemia ’s α2 KK ( 11 ) and β ( 15 ) in Xenopus oocytes were unsuccessful. Therefore, we raised Artemia at three salinities, 250 mM, 2 M, and 4 M salt (mostly NaCl, see Methods ), to perform RNAseq and de novo transcriptome assembly.…”

Structural organization and transcription of the mouse gastric H+, K(+)-ATPase beta subunit gene.

“…The similarities in gene organization and amino acid sequence strongly indicate that the H,KATPase and NaK-ATPase 131 and 12 subunit genes are members of a multigene family and have evolved from a common ancestral subunit gene. It should be noted in this context that the Na,K-ATPase P subunit of an invertebrate, the brine shrimp Artemia salinas (25), shows greater amino acid sequence homology to the rat Na,K-ATPase 13 subunit than it does to the rat 132 subunit. This observation suggests that the gene encoding the Na,K-ATFase P1 subunit most closely resembles the ancestral 13 (Fig.…”