Sperm Surface Protein Profiles of Fertile and Infertile Men: Search for a Diagnostic Molecular Marker

Abstract

The present study was conducted to examine whether there is any difference in the protein profiles of sperm membranes of fertile (n = 37) and infertile (n = 29) men. In the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) procedure, the sperm extracts of fertile and infertile men showed 12-16 major and 8-14 minor common protein bands in various molecular regions. However, there was an additional band of approximately 78 kD present in the sperm extracts of approximately 80% of infertile men that was absent in the sperm extracts of fertile men. In the remaining approximately 20% of the infertile men, it was of relatively weaker intensity. This band was present only in the sperm extracts and not in the seminal plasma, whether of fertile or infertile men, and was designated as the infertility-associated sperm protein (IASP). Antibodies to IASP specifically immunoprecipitated the approximately 78-kD protein from the sperm extracts of only infertile and not the fertile men. In the immunofluorescence technique, the anti-IASP antibodies reacted strongly with the head and/or midpiece regions of morphologically abnormal sperm and cross-reacted with a protein in the equatorial regions of morphologically normal sperm of fertile men. The IASP molecule and its antibodies may provide molecular tools to differentiate between the normal and abnormal sperm, and, thus, may be useful markers for the diagnosis of male-factor infertility.

Sperm cell proteomics

“…Conventional protein extraction and 1-D gel electrophoresis has allowed since few decades ago the identification of anomalies in the protamine content [11,56,[63][64][65][66], in histone content [11,[67][68][69] and in membrane, acrosomal, tail or other proteins in infertile patients [70][71][72]. However, the application of the full potential of the MS to the identification of anomalies in infertile patients is more recent.…”