Elevated nucleotide pyrophosphatase activity in cultured skin fibroblasts from patients with Lowe's syndrome

In previous papers we reported that nucleotide pyrophosphatase (NPPase) activities are markedly elevated in skin fibroblasts from patients with Lowe's syndrome. To reveal the molecular basis for this elevation, we investigated to see whether or not the activities are proportional to the amounts of enzyme protein. Determination of the amounts of NPPase proteins by a radioimmunoassay using monoclonal antibodies revealed that the amounts of NPPase proteins were proportional to the enzyme activities. The NPPase proteins from patients' and normal cells were indistinguishable, after SDS-polyacrylamide gel electrophoresis, on Western blot analysis with staining with polyclonal antibodies raised against denatured NPPase. These data suggested that the elevated NPPase activities in fibroblasts in this disorder resulted from increased amounts of the enzyme proteins.