Junctional adhesion molecule A: expression in the murine epididymal tract and accessory organs and acquisition by maturing sperm.

Study Question: Is junctional adhesion molecule A (JAM-A), a sperm protein essential for normal motility, expressed in the murine post-testicular pathway and involved in sperm maturation?

Summary Answer: JAM-A is present in the prostate and seminal vesicles and in all three regions of the epididymis where it is secreted in epididymosomes in the luminal fluid and can be delivered to sperm in vitro.

What Is Known Already: JAM-A shares with the plasma membrane Ca2+ATPase 4 (PMCA4, the major Ca2+ efflux pump in murine sperm) a common interacting partner, CASK (Ca2+/CaM-dependent serine kinase). JAM-A, like PMCA4, plays a role in Ca2+ regulation, since deletion of Jam-A results in significantly elevated intracellular Ca2+ levels and reduced sperm motility.