Plays a role in normal growth and development. Interacts with mdt-6 and mdt-30. Mainly localizes to the nucleus. Ubiquitously expressed in tissues including epidermal, intestinal, pharyngeal and uterine, and is also expressed in vulval muscle cells and gut granules. Expressed from embryos to adults. Expressed in embryos from the two-fold stage, and is ubiquitously expressed during embryonic and larval stages of development. Viable, but sterile with defective development that is prominent during the late larval stages of development. The developmental defects include a squat body stature referred to as a dumpy phenotype, irregular gut, defective gonadal growth, with incomplete gonad development in some animals, a protruding vulva phenotype, defective uterus and spermatheca formation, and excretory canal defects. RNAi-mediated knockdown results in 44% of animals arresting at either the embryonic or larval stage of development, and in a range of phenotypes including defective molting, protruding vulvae that burst, male tail ray defects and uncoordinated movement. Described as a member of the Mediator complex and a probable MED28 ortholog but shows very low similarity to known MED28 proteins and lacks the Pfam Med28 signature found in known MED28 proteins.