Plays a key role in the sexual differentiation of germ cells by promoting the male fate but suppressing the female fate. Represses the female fate pathways by suppressing meiosis, which in turn results in the promotion of the male fate. Maintains the suppression of meiosis by preventing STRA8 expression, which is required for premeiotic DNA replication, after CYP26B1 is decreased. Regulates the localization of the CCR4-NOT deadenylation complex to P-bodies and plays a role in recruiting the complex to trigger the degradation of mRNAs involved in meiosis. Required for the maintenance of the spermatogonial stem cell population. Not essential for the assembly of P-bodies but is required for the maintenance of their normal state. Interacts with CNOT1, CNOT3, CNOT6L, CNOT7 and CNOT9. More abundant in perinuclear region of the cytoplasm of the germ cells of the adult testis (By similarity). Localizes at P-bodies during gonocyte development. Predominantly expressed in male germ cells. Expressed in self-renewing spermatogonial stem cells and developing gonads. First detectable at 13.5 dpc in the male gonocytes, levels increase until about 16.5 dpc and then slightly decrease by 17.5 dpc (at protein level). Expression is maintained in all male gonocytes during embryogenesis, but becomes confined to a small population of the spermatogonia after birth. The Nanos-type zinc finger is composed of two C2HC motifs, each motif binding one molecule of zinc. It is essential for the translation repression activity of the protein. Mice show a gradual loss of the germ cell population within a few cycles of spermatogenesis which is caused by the depletion of spermatogonial stem cells that produce differentiating spermatogenic cells. Belongs to the nanos family.