Interacts with FEM1B. Highly expressed in testis. The protein first appears in meiotic spermatocytes and becomes abundant in spermatids around stage III-IV (at protein level). The PHTF domain was initially defined as an atypical homeodomain, suggesting that this protein could act as a transcription regulator (By similarity). However, the protein is not found in the nucleus and mainly localizes in the endoplasmic reticulum membrane, suggesting that it does not act as a transcription factor (PubMed:12604659).