Summary
The (Na++K+)-ATPase from eel electroplax membranes is resolved into two polypeptides by means of sodium dodecyl sulfate (SDS) preparative gel electrophoresis. From the literature, the larger polypeptide has been known to have a molecular weight in the range of 85,000 to 135,000, while the molecular weight of the smaller polypeptide is known to be between 40,000 and 60,000. When the two polypeptides are combined with a large/small molar ratio of 1∶2, a very Na+-dependent voltage-in-dependent ionophoric activity is observed. The Na+-specificity is manifested as a near absolute requirement for Na+ in order for the two polypeptides to cause an increase in conductance. Further work with tryptic digests of the two polypeptides suggests that the Na+-dependent ionophoric activity is associated with the smaller polypeptide of (Na++K+)-ATPase.
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This work was initiated while the authors were at the Laboratory of Biophysics at the National Institutes of Health, Bethesda, Maryland.
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Shamoo, A.E., Myers, M. Na+-dependent ionophore as part of the small polypeptide of the (Na++K+)-ATPase from eel electroplax membrane. J. Membrain Biol. 19, 163–178 (1974). https://doi.org/10.1007/BF01869976
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DOI: https://doi.org/10.1007/BF01869976