BIOCHEMICAL AND IMMUNOLOGICAL CHARACTERIZATION OF THE ACROSOME REACTION-INDUCING SUBSTANCE (ARIS) OF HFF

Gel filtration experiments with H-3-progesterone labeled hFF demonstra ted that the AR-inducing activity of hFF might be mediated by a proges terone-binding protein. Further immunological investigations added evi dence in support to ARIS being identical with the SERPIN CBG. Moreover , only the protein-progesterone-complex was able to induce AR. It is s uggested that the CBG-progesterone-complex is, proteolytically cleaved at the plasma membrane of spermatozoa, releasing a high local concent ration of progesterone which leads to induction of the AR. (C) 1994 Ac ademic Press, Inc.