Required for formation of the sperm connecting piece during spermiogenesis. Sperm connecting piece is essential for linking the developing flagellum to the head during late spermiogenesis. May be involved in myosin-based microfilament transport through interaction with myosin subunits. Interacts with MYL6. Specifically localizes to the segmented columns and the capitulum of the sperm connecting piece. Belongs to the SPATA6 family.