Amino-terminal processing of the catalytic subunit from Na+-K+-ATPase

An antipeptide antibody (anti-VGR) was prepared by site-directed mutagenesis and was used to assess the structure of the amino terminus of the alpha1-subunit from sodium-potassium-adenosine triphosphatase (Na+-K+-ATPase). Immunoblot analysis of anti-VGR revealed a 100 kDa alpha-subunit. Binding of the subunit was observed in Escherichia coli containing an alpha1/troponin fusion proteins and in insects infected with baculovirus bearing alpha1 or alpha1T. Green monkey cells transfected with alpha1, however, did not show binding, suggesting that expression of alpha1 requires appropriate co- or posttranslational processing.