Processively dephosphorylates 'Ser-2' and 'Ser-5' of the heptad repeats YSPTSPS in the C-terminal domain of the largest RNA polymerase II subunit. This promotes the activity of RNA polymerase II.
Ubiquitously expressed. Isoform 3 is expressed in heart, brain, placenta, lung, liver, skeletal muscle, kidney and placenta.
Defects in CTDP1 are a cause of congenital cataracts facial dysmorphism and neuropathy syndrome (CCFDN) [MIM:604168]. CCFDN is an autosomal recessive developmental disorder that occurs in an endogamous group of Vlax Roma (Gypsies). The syndrome is characterized by a complex clinical phenotype with seemingly unrelated features involving multiple organs and systems. Developmental abnormalities include congenital cataracts and microcorneae, hypomyelination of the peripheral nervous system, impaired physical growth, delayed early motor and intellectual development, facial dysmorphism and hypogonadism. Central nervous system involvement, with cerebral and spinal cord atrophy, may be the result of disrupted development with superimposed degenerative changes. Affected individuals are prone to severe rhabdomyolysis after viral infections and to serious complications related to general anesthesia (such as pulmonary edema and epileptic seizures).