Protein Inhibitor Of Activated STAT 3 (PIAS3)

E3 SUMO-protein ligase PIAS3 is a member of the PIAS family of transcriptional modulators. The protein functions as a SUMO (small ubiquitin-like modifier)-E3 ligase which catalyzes the covalent attachment of a SUMO protein to specific target substrates. It directly binds to several transcription factors and either blocks or enhances their activity.

Alternatively spliced transcript variants of this gene have been identified, but the full-length nature of some of these variants has not been determined.Gel-shift assays showed that PIAS3 can block MITF DNA-binding activity, and cotransfection of MITF and PIAS3 in NIH 3T3 cells inhibited MITF-driven transcription activity. Interaction between PIAS3 and MITF was independent of STAT3 binding.