Interacts with FEM1B. Widely expressed with highest levels in testis. The PHTF domain was initially defined as an atypical homeodomain, suggesting that this protein could act as a transcription regulator (PubMed:10395808). 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 (By similarity).