Plays a role in embryo pre-implantation development. Colocalizes with NPM1 during interphase. By late prophase, metaphase, anaphase and telophase, associates with the chromosome periphery. By telophase localizes to nucleolar precursor body (NPB) (By similarity). In discrete foci distributed throughout the cytoplasm and nucleoplasm during the 4 to 8 cell stages and the morula stage, but not in the periphery of the NPB. During blastocyst development, becomes increasingly localized to the nucleolus and less to the cytoplasm. At the late blastocyst stage, localized predominantly in the nucleolus. Localized in the nucleolus during interphase and to the perichromosomal sheath during mitosis. Does not colocalize in the cytoplasm with GW182 in P-bodies. May translocate to the nucleolus upon early embryonic development. Expressed in the crypts of Lieberkuhn of the intestine (at protein level). Expressed during early development. Expressed in the epithelium of the embryonic gut tube (at protein level). Arrests embryonic development prior to implantation. Embryos at 3.5 dpc lack the mature, tripartite nucleoli, but instead, contain spheres resembling nucleolar precursor body (NPB), indicating arrest of nucleologenesis. Belongs to the RRM MRD1 family.