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The apical location of the Na,K-ATPase is unusual, because most epithelia distribute the Na,K-ATPase to the basolateral membranes. It is thought that the basolaterallocation depends upon the spectrin/ankyrin complex of the cortical cytoskeleton. We demonstrated that RPE segregates the Na,K-ATPase (red) into microvilli, away from spectrin (green). The spectrin lies along the basolateral membranes and in a terminal web region below the microvilli. Regions of overlap appear yellow. For details see:

Rizzolo LJ, Zhou S: (1995) The distribution of Na+,K+-ATPase and 5A11 antigen in apical microvilli of the retinal pigment epithelium is unrelated to alpha-spectrin. J. Cell Science. 108:3623-3633.

Rizzolo LJ: (1999) Polarization of the Na+K+-ATPase in epithelia derived from the neuroepithelia. Int. Rev. Cytol. 185:195-235.