Immunological cross‐reactivity of fungal and yeast plasma membrane H+‐ATPase

Abstract

The plasma membrane H⁺-ATPases from fungi and yeasts have similar catalytic and molecular properties. A structural comparison has been performed using immunoblot analysis with polyclonal antibodies directed toward the 102 kDa polypeptide of the plasma membrane H⁺-ATPase from Neurospora crassa. A strong cross-reactivity is observed between the fungal H⁺-ATPase and the enzyme from the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. Structural homologies are indicated also by the analysis of the cross-reactive peptides originated by proteolytic digestion of Neurospora and S.cerevisiae purified enzymes. Neither enzyme from these two sources appears to be glycosylated by a highly sensitive concanavalin A affinity assay on blotted proteins. A glycoprotein of M _r 115000 and pI 4.8–5, which comigrates with a cell cycle-modulated protein on 2D gel, is present in partially purified preparations of plasma membrane H⁺-ATPase of S.cerevisiae and it is shown to be structurally unrelated to H⁺-ATPase.