May play a role in acrosome formation in spermatogenesis and in fertilization. Exclusively localized on a peripheral part of acrosome membrane (Golgi phase), localized on the equatorial segment of the acrosome (maturation phase). Expressed in gastric tissues. Down-regulated in gastric cancer. Restriction fragment length polymorphisms (RFLPs) in gastric cancer showed loss of 5 kb fragment in comparison with the corresponding normal tissue. Intron retention. Truncated N-terminus. Extended N-terminus.