The catalytic subunits of Ser/Thr protein phosphatases from Caenorhabditis elegans

The catalytic activities of protein phosphatase 1, 2A, 2B, and 2C were detected in crude extracts of Caenorhabditis elegans with different phosphoprotein substrates and specific inhibitors or activators. The enzymological properties of protein phosphatase 2B as well as those of the catalytic subunits of protein phosphatase 1 and protein phosphatase 2A were determined after partial purification. Gene fragments encoding the catalytic subunits of the protein phosphatase 1-2A-2B superfamily were amplified by polymerase chain reaction and were identified by DNA sequencing. Besides the homologs of protein phosphatase 1, 2B, and X, five protein phosphatase 1-type sequences and four novel protein phosphatase sequences were found. Our data, together with the results of the C. elegans genome project, suggest that this nematode contains an extensive family of Ser/Thr specific protein phosphatases including several up to now biochemically uncharacterized members.