Na+/K+atpase is linked to the spectrin-based membrane cytoskeleton in arterial smooth muscle (ASM) cells

Academic Article

Abstract

  • Na+/K+ATPase colocalizes in smooth muscle cells with Na+/K+ exchanger to caveolae-rich domains of the plasma membrane and it has been postulated that this codistribution contributes to the link between Na+/K+ATPase pumping and Na+Ca+ exchange (Moore et al. Nature 56: 657; 1993). In epithelial cells, the polarized distribution of Na+/K+ATPase is maintained through an interaction with the membrane cytoskeleton proteins ankyrin and spectrin (Nelson & Hammerton. JCB 108: 893; 1989). We have examined whether the segregation of Na+/K+ATPase to the caveolae-rich membrane domain in A7r5 ASM cells and SV40 LT immortalized rat ASM cells is maintained through a similar interaction with ankyrin and spectrin. Biochemical analysis revealed that ∼35% of α1 Na+/K+ATPase was resistant to extraction in buffers containing 0.5% Triton X (TX)-100. Immunofluorescence microscopy of TX-100 extracted cells showed that cytoskeleton associated Na+/K+ATPase had a distribution similar to that of ankyrin, non-erythroid a and β(βG) spectrins. Sucrose gradient centrifugation of TX-100 extracts followed by nondenaturing 3% PAGE and immunoblot analysis of peak Na+/K+ATPase fractions revealed a Na+/K+ ATPase containing band, which co-migrated with ankyrin and o and βspectrin, indicating that these proteins are part of a high molecular weight complex. These data suggest that an interaction with ankyrin and spectrin is involved in maintaining the distribution of a, Na+/K+ATPase to the caveolae-rich domain in ASM cells.
  • Authors

    Published In

  • The FASEB Journal  Journal
  • Pubmed Id

  • 12661337
  • Author List

  • Lee D; Chen X; Smith PR
  • Volume

  • 10
  • Issue

  • 3