Functional significance of the oligomeric structure of the Na,K-pump from radiation inactivation and ligand binding

Journal Article · Tue Jan 01 04:00:00 EST 1991 · Society of General Physiologists Series; (United States)

OSTI ID:5011738

Norby, J G; Jensen, J ^[1]

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1. Institute of Biophysics, University of Aarhus (Denmark)

The present article is concerned with the oligomeric structure and function of the Na,K-pump (Na,K-ATPase). The questions we have addressed, using radiation inactivation and target size analysis as well as ligand binding, are whether the minimal structural unit and the functional unit have more than one molecule of the catalytic subunit, alpha. The authors first discuss the fundamentals of the radiation inactivation method and emphasize the necessity for rigorous internal standardization with enzymes of known molecular mass. They then demonstrate that the radiation inactivation of Na,K-ATPase is a stepwise process which leads to intermediary fragments of the alpha-subunit with partial catalytic activity. From the target size analysis it is most likely that the membrane-bound Na,K-ATPase is structurally organized as a diprotomer containing two alpha-subunits. Determination of ADP- and ouabain-binding site stoichiometry favors a theory with one substrate site per (alpha beta) 2. 47 references.

• OSTI ID: 5011738
• Journal Information: Society of General Physiologists Series; (United States), Journal Name: Society of General Physiologists Series; (United States) Vol. 46; ISSN SGPHA; ISSN 0094-7733
• Country of Publication: United States
• Language: English

Related Subjects

560120* -- Radiation Effects on Biochemicals
Cells
& Tissue Culture
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ACID ANHYDRASES
ALKALI METALS
ATP-ASE
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
CELL CONSTITUENTS
CELL MEMBRANES
ELEMENTS
ENZYMES
HYDROLASES
INACTIVATION
KINETICS
LIGANDS
MEMBRANE TRANSPORT
MEMBRANES
METALS
MOLECULAR STRUCTURE
PHOSPHOHYDROLASES
POTASSIUM
RADIATION EFFECTS
REACTION KINETICS
SODIUM
STOICHIOMETRY