Involved in the maintenance of embryonic stem (ES) cell pluripotency. Dispensable for self-renewal of pluripotent ES cells and establishment of germ cells. Associates with specific target mRNAs. Pluripotent cell-specific. Expressed in zygotes, cleavage-stage embryos and blastocysts, embryonic stem (ES) and embryonic germ (EG) cells. Detected in both the trophectoderm (TE) and inner cell mass (ICM) of blastocysts. More abundant in the ICM than TE at 3.5 dpc blastocyst stage. Expressed in primordial germ (PGC) cells from 10.5 to 13.5 dpc. Expressed in developing gonads from 11.5 to 15.5 dpc. Progressively undetectable in ovary from 13.5 to 15.5 dpc. Undetectable in testis after 15.5 dpc. Not expressed in somatic cells at 13.5 dpc (at protein level). Expressed in embryonic stem (ES) and embryonic carcinoma (EC) cells. Not detected during the differentiation of stem cells or midgestation embryos nor in neonatal tissues. Weakly expressed or not detected in oocytes and fertilized eggs. Down-regulated by retinoic acid in embryonic carcinoma (EC) cells and in developing germ cells. Mice develop normally and are fertile. ES cells derived from these mice demonstrate normal morphology, proliferation and differentiation. Belongs to the KHDC1 family.