Phosphorylation of a 15 K axonemal protein is the trigger initiating trout sperm motility

Abstract

The plasma membrane of trout sperm was removed by the treatment with Triton X-100 and phosphorylation of sperm protein was analyzed by SDS-polyacrylamide gel electrophoresis after incubating the demembranated sperm with [γ-32P]ATP. When the motility of demembranated sperm was initiated by addition of cAMP, a 15 K protein was strongly phosphorylated within 1 sec, a time period compatible with the normal initiation of sperm motility. When sperm were first allowed to swim and then demembranated, cAMP-dependent phosphorylation of the 15 K protein was not observed. The results suggest that the 15 K protein, completely phosphorylation in 1 sec in the presence of cAMP, triggers the initiation of sperm motility.