The adhesion molecule on glia (AMOG/β2) and α1 subunits assemble to functional sodium pumps in Xenopus oocytes

G. Schmalzing, S. Kroner, M. Schachner, S. Gloor

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Abstract

The adhesion molecule on glia, AMOG, an integral cell surface glycoprotein highly expressed by cerebellar astrocytes and involved in neuron to astrocyte adhesion and granule neuron migration (Antonicek, H., Persohn, E., and Schachner, M. (1987) J. Cell Biol. 104, 1587-1595) has been identified as a β2 subunit isoform of the mouse sodium pump (Gloor, S., Antonicek, H., Sweadner, K. J., Pagliusi, S., Frank, R., Moos, M., and Schachner, M. (1990) J. Cell Biol. 110, 165-174). Here we demonstrate that AMOG/β2 expressed by cRNA injection in Xenopus oocytes is capable of combining with endogenous Xenopus α1 subunits or coexpressed Torpedo α1 subunits to yield a functional α1/AMOG sodium pump isozyme. Determinations of the number of ouabain binding sites and ouabain-sensitive 86Rb+ uptake suggest that the α1/AMOG isozyme has slightly lower maximum transport rate and apparent affinity for external K+ than the α1/β1 isozyme. Immunoprecipitation of α1/AMOG complexes from digitonin extracts of [35S]methionine-labeled oocytes with a monoclonal anti-AMOG antibody provides direct evidence for a stable association between AMOG and the α1 subunits of Xenopus and Torpedo.

Original languageEnglish (US)
Pages (from-to)20212-20216
Number of pages5
JournalJournal of Biological Chemistry
Volume267
Issue number28
StatePublished - 1992
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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