Contributes to normal sperm motility, but not essential for male fertility. Interacts with PRM2. Mainly nuclear. Also detected in cytoplasm near the midpiece of the flagellum. Expressed in spermatogenic cells, especially in spermatocytes (at protein level). The poly-Ala region seems to be polymorphic and the number of Ala varies between 4 and 6. Belongs to the TDRP family.