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Pig kidney Na+,K+-ATPase. Primary structure and spatial organization.
FEBS Letters
|June 9, 1986
Summary
Researchers cloned and sequenced pig kidney sodium-potassium adenosine triphosphatase (Na+,K+-ATPase) alpha- and beta-subunits. Structural analysis of peptides informed a model of the transmembrane arrangement of these critical enzyme components.
Area of Science:
- Biochemistry
- Molecular Biology
- Membrane Protein Structure
Background:
- Na+,K+-ATPase is a vital ion pump in cell membranes.
- Understanding its structure is key to comprehending ion transport.
- Previous models lacked detailed transmembrane arrangement data.
Purpose of the Study:
- To clone and sequence cDNAs for pig kidney Na+,K+-ATPase alpha- and beta-subunits.
- To elucidate the transmembrane topology of the Na+,K+-ATPase.
- To provide structural insights into the enzyme's function.
Main Methods:
- Complementary DNA (cDNA) cloning and sequencing of alpha- and beta-subunits.
- Selective tryptic hydrolysis of membrane-bound alpha-subunit.
- Tryptic hydrolysis of immobilized isolated beta-subunit.
Main Results:
- The mature alpha-subunit has 1016 amino acid residues; the beta-subunit has 302.
- Structural data obtained from peptide fragments of extramembrane regions (alpha-subunit) and glycopeptides (beta-subunit).
- These data support a model for the transmembrane arrangement of Na+,K+-ATPase polypeptide chains.
Conclusions:
- A detailed model for the transmembrane arrangement of Na+,K+-ATPase subunits was developed.
- The study provides crucial structural information for understanding ion pump mechanisms.
- This work enhances knowledge of membrane protein topology and function.