Molecular cloning and characterization of alpha-subunit isoforms of the Na,K-ATPase.

The identification of the different alpha-subunit isoforms of the Na,K-ATPase has added an unexpected complexity to the understanding of the function and regulation of this important transport protein. Our results indicate that the alpha, alpha(+) and alpha III isoform mRNAs have distinct, but partially overlapping, distributions in brain and peripheral tissues. Also, characterization of mRNA distribution in fetal tissues suggests that the Na,K-ATPase alpha-subunit isoforms are regulated during development and differentiation. The developmental regulation and strikingly different tissue specificities of the three alpha-subunit isoforms suggests that the different Na,K-ATPase alpha-subunits may be adapted to perform different roles in maintaining sodium and potassium homeostasis.