Primary Structure of the α-Subunit of Human Na, K-ATPase Deduced from cDNA Sequence1

Abstract

Clones carrying cDNA sequences for the alpha-subunit of the Na,K-ATPase from HeLa cells have been isolated. Nucleotide sequence analysis of the cloned cDNA has revealed the primary structure of this polypeptide, which consists of 1,023 amino acids. The alpha-subunit of the human Na,K-ATPase exhibited 87% homology with its Torpedo counterpart and 98% homology with its sheep counterpart. The six putative transmembrane segments M1-M6 showed higher conservation than the total segments. Total genomic Southern hybridization indicated the existence of at most two copies, possibly only one, of the gene encoding the Na,K-ATPase alpha-subunit in the human genome.

Na,K-ATPase subunit isoforms in human reticulocytes: Evidence from reverse transcription–PCR for the presence of α1, α3, β2, β3, and γ

“…To explore whether alternative splicing or RNA editing was involved, we sequenced the whole coding region of the reticulocyte ␣1 subunit. We found no difference between the DNA sequence of reticulocyte Na,K-ATPase and the published sequence for the human ␣1 isoform (19). Although we were unable to obtain the ␣1 subunit in one piece, we did obtain overlapping PCR products that covered the entire coding region (Fig.…”

Identification of a region within the Na,K-ATPase alpha subunit that contributes to differential ouabain sensitivity.

“…Sequencing of the clone revealed 100% identity with the sequence previously reported for human al subunit cDNA (16). The cDNA fragment was isolated from Xgtll by digestion with AatII and HgiAI, linked with HindIII, and inserted into pSV2HS to yield expression vector pSV2Hal.…”

Family of human Na+,K+‐ATPase genes Structure of the gene for the catalytic subunit (αIII‐form) and its relationship with structural features of the protein

“…Its comparison with the known structures of analogous subunits of other Na÷,K÷-ATPases unravels the following specific features. It is ten residues shorter than the precursor of the catalytic subunit of the enzyme (or-form) from HeLa cells [16]. The total number of amino acid distinctions in these proteins is 139, of them 32 are concentrated in the N-terminus, the most variable part of E1E2 ion-transporting ATPases (residues 1-59), the sequence of the first 11 residues completely differs from the corresponding regions of other forms.…”

“…At present, the structures of several animal iontransporting ATPases of the E~E2 typeNa+,K+-ATPases [1,3,7,9,16,19,23,24], H+,K +-ATPase [25], and Ca2+-ATPases [26] -are defined by analysis of cDNA nucleotide sequences. Comparison of the known primary structures including that described above revealed several structural regions highly conservative among all these related enzymes.…”