Enables RNA polymerase II cis-regulatory region sequence-specific DNA binding activity; chromatin binding activity; and transcription coactivator activity. Acts upstream of or within several processes, including Wnt signaling pathway; chordate embryonic development; and glial cell development. Part of mediator complex. Is expressed in brain. Human ortholog(s) of this gene implicated in FG syndrome; leiomyosarcoma; major depressive disorder; phobic disorder; and syndromic X-linked intellectual disorder Lujan-Fryns-type. Orthologous to human MED12 (mediator complex subunit 12). [provided by Alliance of Genome Resources, Apr 2022]