Component of the Mediator complex, a coactivator involved in the regulated transcription of nearly all RNA polymerase II-dependent genes. Mediator functions as a bridge to convey information from gene-specific regulatory proteins to the basal RNA polymerase II transcription machinery. The Mediator complex, having a compact conformation in its free form, is recruited to promoters by direct interactions with regulatory proteins and serves for the assembly of a functional preinitiation complex with RNA polymerase II and the general transcription factors. Involved in the repression of phenylpropanoid biosynthesis. May compete with MED33B for common binding partners or for occupancy in Mediator. Component of the Mediator complex. Ubiquitous. No visible phenotype. Belongs to the Mediator complex subunit 33 family.