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 (PIC) with RNA polymerase II and the general transcription factors. The essential med11/22 heterodimer specifically functions in promoting stable PIC formation (By similarity). Component of the Mediator complex, which is composed of at least 21 subunits that form three structurally distinct submodules. The Mediator head module, the middle module, and the tail module. The head and the middle modules interact directly with RNA polymerase II, whereas the elongated tail module interacts with gene-specific regulatory proteins (By similarity). Med11 is part of the head module. Forms a heterodimer with med22. The med11/22 heterodimer binds to and stabilizes the central head subunit med17. Belongs to the Mediator complex subunit 11 family.