The Saccharomyces cerevisiae type 2A protein phosphatase (PP2A) Pph22p differs from the catalytic subunits of PP2A (PP2Ac) present in mammals, plants and Schizosaccharomyces pombe by a unique N-terminal extension of approximately 70 amino acids. We have overexpressed S. cerevisiae Pph22p and its N-terminal deletion mutant DN-Pph22p in the GS115 strain of Pichia pastoris and purified these enzymes to apparent homogeneity.