Transcription regulator of both male and female germline differentiation. Suppresses genes involved in spermatogonial stem cells maintenance, and induces genes important for spermatogonial differentiation (PubMed:22056784). Coordinates oocyte differentiation without affecting meiosis I (PubMed:28504655). Forms both hetero- and homodimers with SOHLH1. Translocates from the cytoplasm into the nucleus and the translocation is dependent on SOHLH1 protein expression. Preferentially expressed in the adult ovary and testis. Expressed in the majority of spermatogonia in adult animals, but not in the most undifferentiated spermatogonial population (PubMed:22056784). In the embryonic gonads it is expressed as early as 13.5 dpc and later. In 3-day-old postnatal ovaries, it is expressed within oocytes in germ cell clusters and primordial follicles. In the adult, it is expressed only in small follicles, primary primordial and primary follicles. In testis, it is exclusively present in spermatogonia. Present at postnatal day 5, when spermatogonia stem cells differentiate into type A spermatogonia. Absent in Sertoli cells or spermatocytes (at protein level). Expressed in the germline as early as 12.5 dpc and precedes SOHLH1 protein expression, which occurred circa 15.5 dpc. SOHLH1 appearance at 15.5 dpc correlates with SOHLH2 translocation from the cytoplasm into the nucleus (PubMed:28504655). Up-regulated in mice lacking Sohlh1. Knockout mice are infertile. Infertility could not be rescued by SOHLH1 or SOHLH2 transgene expression due to a lack of expression of either genes in rescued animals.