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(521) ROLE OF MOUSE ADAM2 DISINTEGRIN ON SPERM-ZONA BINDING. Takahashi, Yuji1, Tomczuk, Monika1, 1 Department of Cell Biology, Charlottesville, VA ABSTRACT- ADAM2 and ADAM3 are glycoproteins on sperm plasma membrane. They are known to be involved in sperm-egg binding at the plasma membrane level. Gene targeting of these molecules raised possibility that ADAM2 and ADAM3 might be involved in sperm-zona binding. Here, we report the possible interaction of ADAM2 disintegrin domain with zona pellucida glycoprotein ZP2. Mouse ADAM2 (mADAM2) and mADAM3 disintegrin domains produced in E. coli were subjected to biological assays including sperm-zona binding assay and bead binding assay. The binding of mADAM2 disintegrin domain to zonae pellucidae was seen by immunofluorescence and bead binding assays, whereas mADAM3 was not. Only mADAM2 disintegrin inhibited sperm binding to zona-intact eggs in a dose-dependent manner. Polyclonal anti mADAM2 loop antibody inhibited sperm-zona binding and mADAM2 bead binding. On the other hand, the disintegrin mutant without loop did not decrease the biological activities, suggesting that mADAM2 disintegrin binding to zonae was mediated via the loop. Affinity chromatography of zona proteins on mADAM2 disintegrin revealed that the possible binding partner for mADAM2 disintegrin was ZP2. Furthermore, the binding of mADAM2 to zona-intact eggs was inhibited by anti ZP2, but not by anti ZP3. These results suggest that ADAM2 disintegrin domain binds to ZP2 through the disintegrin loop. Our finding gives a new insight for sperm-zona interaction. KEY WORDS: ADAM2, zona, sperm, fertilization |
