Predicted to enable thyroid hormone receptor binding activity and transcription coactivator activity. Predicted to be involved in positive regulation of transcription initiation from RNA polymerase II promoter and transcription by RNA polymerase II. Part of mediator complex. Is expressed in 1st branchial arch; genitourinary system; limb; and trunk somite. Orthologous to human MED4 (mediator complex subunit 4). [provided by Alliance of Genome Resources, Apr 2022]