The human sperm protein PH-20 has hyaluronidase activity

The PH-20 protein present on the membrane of guinea pig sperm was characterized using a monoclonal antibody [(1991) J. Cell Biol. 111, 2939-2949]. We have isolated the cDNA encoding the human PH-20 protein from a testis library. This cDNA was expressed in RK 13 cells using a vaccinia virus expression system. Cells expressing the human PH-20 protein possess hyaluronidase activity. Treatment with PI-PLC releases the hyaluronidase into the the medium with a concomitant large increase in enzymatic activity. These results demonstrate that the human PH-20 protein has hyaluronidase activity.