Protein Phosphatase, Mg2+/Mn2+ Dependent 1J (PPM1J)

Kashiwaba et al. (2003) cloned mouse Ppm1j, which the authors called protein phosphatase-2C-zeta. The deduced protein contains 6 motifs conserved among all mammalian PP2C family members. It has a unique N-terminal region and a proline-rich domain between conserved motifs II and III. Recombinant Ppm1j protein showed Mg(2+)- or Mn(2+)-dependent protein phosphatase activity. Northern blot analysis detected a 1.7-kb Ppm1j transcript exclusively in testicular germ cells.Using Ppm1j as bait in a yeast 2-hybrid analysis of an adult mouse testis library, Kashiwaba et al. (2003) identified ubiquitin-conjugating enzyme-9 (UBE2I) as a binding partner with Ppm1j. GST pull-down assays in COS-7 cells confirmed the binding of Ppm1j with Ube2i, and showed that this binding is greatly enhanced by small ubiquitin-related modifier-1 (SUMO1).