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. Mediator is recruited to promoters by direct interactions with regulatory proteins and serves as a scaffold for the assembly of a functional preinitiation complex with RNA polymerase II and the general transcription factors (By similarity). Required for the development of dopaminergic amacrine cells in the retina. May also negatively regulate the development of rod photoreceptor cells. Component of the Mediator complex. Maternally expressed. Ubiquitously expressed throughout development. Belongs to the Mediator complex subunit 27 family.