Carboxy-terminal domain RNA polymerase II polypeptide A small phosphatase 1 (CTDSP1)

Preferentially catalyzes the dephosphorylation of 'Ser- 5' within the tandem 7 residue repeats in the C-terminal domain (CTD) of the largest RNA polymerase II subunit POLR2A. Negatively regulates RNA polymerase II transcription, possibly by controlling the transition from initiation/capping to processive transcript elongation.

Recruited from REST to neuronal genes that contain RE-1 elements, resulting in neuronal gene silencing in non-neuronal cells. .