Synthesis, processing, and subcellular localization of mouse ADAM3 during spermatogenesis and epididymal sperm transport

Abstract

To elucidate synthesis, processing, and subcellular localization of mouse ADAMS (cyritestin) during spermatogenesis and epididymal sperm transport, we carried out immunoblotting and immunohistochemical analysis of testicular germ cells, and epididymal and vas deferens sperm, using affinity-purified anti-ADAMS antibody. ADAMS was initially synthesized as a 110-kDa precursor in round spermatids, and the precursor was then processed into a 42-kDa mature protein during the sperm transport into and/or once in the epididymis. The mature ADAMS was localized on the anterior part of capacitated sperm heads and was rapidly removed from the head region during the calcium ionophore A23187-induced acrosome reaction. These results demonstrate that the mature form of ADAMS is involved in the binding of sperm to the egg zona pellucida, not in the membrane fusion between sperm and egg.