Protein Phosphatase 5 (C Terminal)

Protein phosphatase 5 (PP5) is a novel human protein serine/threonine phosphatase of molecular weight of 58 kDa. It is made up of a C-terminal phosphatase catalytic domain and an N-terminal domain, which has four repeats of 34 amino acids, three of which are tandemly arranged. The phosphatase domain contains all of the invariant motifs of the PP1/PP2A/PP2B gene family. However, it is not closely related to any other known member of this family of phosphatases. Thus it makes up a new subfamily of phosphatases. PP5 expressed in bacteria has been shown to dephosphorylate serine residues in proteins and is more sensitive than PP1 to the tumor promoter okadaic acid. PP5 appears to be localized to the nucleus suggesting that, like other nuclear tetratricopeptide (TPR)-containing proteins, it may playa role in the regulation of RNA biogenesis and mitosis.