E3 SUMO-protein ligase PIAS3 (PIAS3)

Functions as an E3-type little ubiquitin-like modifier (SUMO) ligase, stabilizing the interaction between UBE2I and the substrate, and as a SUMO-tethering factor. Plays a crucial role as a transcriptional coregulation in various cellular pathways, including the STAT pathway and the steroid hormone signaling pathway.

Involved in regulating STAT3 signaling through inhibiting STAT3 DNA-binding and controlling cell growth. Enhances the sumoylation of MTA1 and might participate in its paralog-selective sumoylation (PubMed:21965678, PubMed:9388184).