May be involved in the later stages of fibrous sheath biogenesis and spermatozoa capacitation. Inhibits ROPN1 and ROPN1L SUMOylation. Binds calcium. Interacts with CABYR. Interacts with ROPN1 and ROPN1L; the interaction increases upon spermatozoa capacitation conditions. Localizes to cortex of the fibrous sheath including the surface of the longitudinal columns and ribs of the principal piece of sperm flagella. Phosphorylated by PKA upon spermatozoa capacitation conditions.