Identification of the cofilin-binding sites in the large cytoplasmic domain of Na,K-ATPase

Miyoung Kim, Jaehoon Jung, Chul Seung Park, Kyunglim Lee

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9 Scopus citations


Na,K-ATPase, an α, β heterodimer, is found in the plasma membrane of all animal cells. The α chain is believed to have 10 transmembrane regions and a large cytoplasmic domain between the 4th and 5th transmembrane regions (H4-H5). In our previous report, the large (3rd) cytoplasmic domains of the α1 and α2 isoform were found to interact with cofilin, an actin-modulating protein, by the yeast two-hybrid system. Here we show that cofilin interacts only with the 3rd cytoplasmic domain of the α2 subunit but not with the 2nd, 4th, and 5th cytoplasmic domains or the cytoplasmic region of the β subunit of Na,K-ATPase. We also demonstrate that cofilin interacts with the large cytoplasmic domains of the α1, α2 and α3 isoforms of Na,K-ATPase, but not with those of glucose transporter 1, glucose transporter 4, cystic fibrosis transmembrane conductance regulator and plasma membrane Ca-ATPase. We introduced 10 mutations into the 3rd cytoplasmic domain of Na,K-ATPase to identify the binding sites with cofilin. Eight of these mutants were single amino acid substitutions (R417Q, K470Q, K654G, D672A, K691A, R700G, R700A and D710G) and two were double mutant (K654GR700G and K719AK720A). Analysis of the activity of the reporter gene of these mutants shows that residues D672 and R700 of the 3rd cytoplasmic domain of Na,K-ATPase are involved in the interaction with cofilin.

Original languageEnglish
Pages (from-to)1021-1029
Number of pages9
Issue number10
StatePublished - 1 Oct 2002

Bibliographical note

Funding Information:
We thank Dr. Guido Guidotti for his critical review of the manuscript. This work was supported by the Korea Science and Engineering Foundation through the Center for Cell Signaling Research at Ewha Womans University and by the 21 C Frontier for Functional Genome Analysis of Human Genome. M. Kim was supported by a Brain Korea Project fellowship.


  • Cofilin-binding sites
  • Mutation
  • Transmembrane protein
  • Yeast two-hybrid


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