| Modification Notes |
Mitogen-activated protein (MAP) kinases are a large class of proteins involved in signal transduction pathways that are activated by a range of stimuli and mediate a number of physiological and pathological changes in the cell. Dual specificity phosphatases (DUSPs) are a subclass of the protein tyrosine phosphatase (PTP) gene superfamily, which are selective for dephosphorylating critical phosphothreonine and phosphotyrosine residues within MAP kinases. DUSP gene expression is induced by a host of growth factors and/or cellular stresses, thereby negatively regulating MAP kinase superfamily members including MAPK/ERK, SAPK/JNK and p38. One member of this subfamily, PIR1, (phosphatase that interacts with RNA/RNP complex 1, also designated dual specificity protein phosphatase 11) removes two phosphates from the 5'-triphosphate end of RNA, but not from mononucleotide triphosphates. PIR1 interacts with splicing factors 9G8 and SRp30C, and may participate in nuclear mRNA metabolism. |