Isoform Specific Antisera for the Na⁺/K⁺-ATPase β1 and β2 Subunits: Localization in Fetal Rat Tissues

Abstract

In the Na⁺/K⁺-ATPase system, the alpha subunit has been implicated in the ion pumping process and the ß subunit has no known role in ion transport. Two different isoforms of the ß subunit (ß1 and ß2) have been described in mammals (3). The ß2 isoform is an adhesion molecule on glial cells (AMOG), specifically involved in neuron-astrocyte adhesion (1). The ß2 isoform has no obvious adhesion function in other cell types, and no adhesion function whatsoever has been reported for the ß1 isoform. In order to understand further the localization and functional implications, we have generated a series of isoform-specific antibodies against the human Na⁺/K⁺-ATPase ß1 and ß2 isoforms. Polyclonal rabbit antisera were raised against truncated ß-isoform molecules. These proteins were made in E. coli with pET expression vectors (5). Immunohistochemical preparations of 15-days-old whole rat embryos and on nerve cell cultures obtained from those, showed an specific staining pattern, particularly enhanced in the apical membrane of ear semicircular ducts and choroid plexus.