The structure of the vacuolar ATPase in Neurospora crassa.

The filamentous fungus Neurospora crassa contains many small vacuoles. These organelles contain high concentrations of polyphosphates and basic amino acids, such as arginine and ornithine. Because of their size and density, the vacuoles can be separated from other organelles in the cell. The ATP-driven proton pump in the vacuolar membrane is a typical V-type ATPase. We examined the size and structure of this enzyme using radiation inactivation and electron microscopy. The vacuolar ATPase is a large and complex enzyme, which appears to contain at least thirteen different types of subunits. We have characterized the genes that encode eleven of these subunits. In this review, we discuss the possible function and structure of these subunits.