The PH‐20 Protein in Human Spermatozoa
1997; Wiley; Volume: 18; Issue: 2 Linguagem: Inglês
10.1002/j.1939-4640.1997.tb01895.x
ISSN2047-2927
AutoresKhalida Sabeur, Gary N. Cherr, Ashley I. Yudin, Paul Primakoff, MING‐WEN LI, James W. Overstreet,
Tópico(s)Advanced Drug Delivery Systems
ResumoABSTRACT: PH‐20 is a sperm plasma‐membrane protein that has been shown to have hyaluronidase activity in several mammalian species including nonhuman primates. In this investigation, the PH‐20 protein was characterized in noncapacitated human sperm and in capacitated human sperm. Two forms of PH‐20 were observed in immunoblots of sodium dodecylsulfate polyacrylamide‐gel electrophoresis (SDS PAGE) using a polyclonal antibody to recombinant PH‐20: a major band of 64 kDa appeared in noncapacitated and capacitated sperm extracts and a 53‐kDa band that appeared only in the acrosome‐reaction supernatant of acrosome‐reacted sperm. Using hyaluronic acid substrate gel analysis, we demonstrated that noncapacitated sperm extracts, capacitated sperm extracts, and the acrosome‐reaction supernatant had hyaluronidase activity at neutral pH (pH 7) and acid pH (pH 4). The 64‐kDa form in all samples had hyaluronidase activity at both neutral and acid pH, but the 53‐kDa form was only active at acid pH. Total hyaluronidase activity, as measured by a microplate assay, was higher at pH 7 than at pH 4. Very low hyaluronidase activity was detected in the acrosome‐reaction supernatant. Transmission electron microscopy and immunogold labeling showed that PH‐20 of acrosome‐intact human sperm was located on the plasma membrane over the entire head but not on the sperm midpiece and tail. After the acrosome reaction, PH‐20 was also located on the inner acrosomal membrane. The biochemical characteristics and the ultrastructural localization of PH‐20 in human sperm suggest that this protein is the human sperm hyaluronidase and, therefore, has an important function during fertilization.
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