Protein Phosphatase Classification: PPP/PP4※ PP4 family introduction PP4, a family of PPP which is ubiquitously expressed in all eukaryotes, is composed of three subunits, including two regulatory subunits R1 and R2, a catalytic subunit. PP4 is highly conserved among eukaryotes and sequence identity among human, mouse and rabbit is about 99% (1), which suggests that PP4 is an important type of protein phosphatases. PP4 is localized in mitotic centrosomes and plays a critical role in centrosome maturation. In addition, PP4 is also involved in varieties of cellular signaling, such as NF-kB pathway, Jnk pathway and apoptotic signaling. What's more, PP4 has been reported to possess a nuclear function, for example, PP4 is essential for stalled replication forks stabilization and is involved in formation or maintenance of chiasmata (2).
Reference
1. Hu, M.C., Shui, J.W., Mihindukulasuriya, K.A. and Tan, T.H. (2001) Genomic structure of the mouse PP4 gene: a developmentally regulated protein phosphatase. Gene, 278, 89-99. PMID: 11707325
2. Cohen, P.T., Philp, A. and Vazquez-Martin, C. (2005) Protein phosphatase 4--from obscurity to vital functions. FEBS Lett, 579, 3278-3286. PMID: 15913612
PPP PP4 in eukaryotes:
1. Hu, M.C., Shui, J.W., Mihindukulasuriya, K.A. and Tan, T.H. (2001) Genomic structure of the mouse PP4 gene: a developmentally regulated protein phosphatase. Gene, 278, 89-99. PMID: 11707325
2. Cohen, P.T., Philp, A. and Vazquez-Martin, C. (2005) Protein phosphatase 4--from obscurity to vital functions. FEBS Lett, 579, 3278-3286. PMID: 15913612
PPP PP4 in eukaryotes: