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 proliferation of enteric nervous system precursors. Required for the development of dopaminergic amacrine cells and rod photoreceptor cells in the retina. Component of the Mediator complex. Maternally expressed. Ubiquitously expressed through the 10 somite stage. Expression subsequently decreases in the trunk and tail while remaining high in anterior parts of the embryo. By 24 hours post-fertilization (hpf) expression is no longer detectable in the trunk and tail, but is maintained in anterior parts of the embryo. At 48 hpf expression extends along almost the entire length of the gut and is particularly high in the dorsal forebrain, ventral midbrain, and the dorsal posterior part of the midbrain. At 60 hpf, expression in the gut is restricted to intestinal epithelial cells. At 72 hpf, expression in the CNS is limited to cells in the diencephalon, the ventral midbrain and the dorsal part of the midbrain, while expression outside the CNS is restricted to the pharyngeal endoderm. Expression in the pharyngeal endoderm persists through 96 hpf. Belongs to the Mediator complex subunit 24 family.