The K+-induced apparent heterogeneity of high-affinity nucleotide-binding sites in (Na+ + K+)-ATPase can only be due to the oligomeric structure of the enzyme.


K+ induces an apparent heterogeneity among an otherwise homogeneous population of nucleotide-binding sites in (Na+ + K+)-ATPase preparations from pig kidney. With the help of ouabain we show that this heterogeneity cannot be due to a mixture of different and independent sites and conclude that each enzyme molecule must contain two nucleotide site-containing… (More)