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. Flowering regulator which suppresses FLC expression, promotes FT and TSF expression and up-regulates SOC1 and FUL mainly in an FT-dependent manner under long-day conditions. Involved in diverse developmental aspects through gene regulation and modulation of the auxin response. Acts closely together with MAB13. Involved in the regulation of embryo patterning and cotyledon organogenesis by transiently repressing a transcriptional program that interferes with this process. Component of the Mediator complex. Ubiquitous. Higher expression in vascular tissue, shoot apex and developing floral organs. Expressed first at the dermatogen stage of embryogenesis and then in all cells of the embryo and suspensor through the globular stage. Decreases in the periphery of the hypocotyl and on the abaxial side of cotyledons from the heart stage to the torpedo stage, and by the bent cotyledon stage, restricted to the vascular tissue and the shoot and root apical meristems. Abnormal embryo and cotyledon development, and embryo lethality in some cases. When viable, plants are small, with abnormal leaf shape and vascular patterning, ectopic bract-like organs and greatly delayed flowering time and sterile flowers. Belongs to the Mediator complex subunit 12 family.