Phosphoprotein phosphatase from yeast and its ribosomal substrate

Phosphoprotein phosphatase was isolated from yeast postribosomal supernatant and partly characterized. The enzyme preferentially dephosphorylated phospho-casein and acidic ribosomal proteins L44 and L45, the eukaryotic analogues of bacterial proteins L7 and L12. The evidence suggests that this enzyme is not a catalytic subunit of the multifunctional phosphoprotein phosphatase present in most eukaryotic organisms.