Detection of P2 precursors in the sperm cells of infertile patients who have reduced protamine P2 levels

Objective: To determine whether the reduction in the protamine P2 content (increased P1/P2 ratio) reported in some infertile patients could result from incomplete processing of protamine P2 precursors. Design: Analysis of samples with a marked reduction in the protamine P2 content using polyacrylamide gel electrophoresis and subsequent detection of protamine P2 precursors through Western blot analysis. Setting: University departments and laboratories. Patient(s): One hundred eighty-four men undergoing an evaluation for infertility. Main Outcome Measure(s): Comparative Western blot analysis of nuclear sperm proteins using specific antibodies to protamine P1 and protamine P2. Result(s): After selection of the samples with a marked reduction of the protamine P2 content and subsequent analysis by Western blot, a small proportion of putative P2 precursors was detected in most samples, whereas a significant increase was detected in two of them. Conclusion(s): In some infertile men, a reduction in the protamine P2 content relative to protamine P1 (increased P1/P2 ratio) is detected concomitant with an increase in the amount of putative P2 precursors. This could represent the first report of incomplete processing of a nuclear sperm protein in humans. (C) 1998 by American Society for Reproductive Medicine.).