An ion-transporting ATPase encodes multiple apical localization signals

Cara J. Gottardi*, Michael J. Caplan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

131 Scopus citations


Epithelial cells accumulate distinct populations of membrane proteins at their two plasmalemmal domains. We have examined the molecular signals which specify the differential subcellular distributions of two closely related ion pumps. The Na,K-ATPase is normally restricted to the basolateral membranes of numerous epithelial cell types, whereas the H,K-ATPase is a component of the apical surfaces of the parietal cells of the gastric epithelium. We have expressed full length and chimeric H,K-ATPase/Na,K-ATPase cDNAs in polarized renal proximal tubular epithelial cells (LLC-PK1). We find that both the α and β subunits of the H,K-ATPase encode independent signals that specify apical localization. Furthermore, the H,K-ATPase β-subunit possesses a sequence which mediates its participation in the endocytic pathway. The interrelationship between epithelial sorting and endocytosis signals suggested by these studies supports the redefinition of apical and basolateral as functional, rather than simply topographic domains.

Original languageEnglish (US)
Pages (from-to)283-293
Number of pages11
JournalJournal of Cell Biology
Issue number2
StatePublished - Apr 1993

ASJC Scopus subject areas

  • Cell Biology


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