Interactions between sperm and zona pellucida (ZP) during mammalian fertilization are not well characterized at the molecular level. To identify sperm proteins that recognize ligand ZP3, we used sonicated sperm membrane fractions as competitors in a quantitative binding assay. Sonicated membranes were density fractionated into 4 fractions. Bands 1–3 contained membrane vesicles, and band 4 contained axonemal and midpiece fragments. In competitive binding assays, bands 1, 2, and 3 but not band 4 were able to compete with live, capacitated, intact sperm for soluble 125I-ZP binding. Affinity-purified ZP fractions consisting of a ZP3-enriched fraction (125I-ZP3) and a fraction enriched for ligands ZP1 and ZP2 and depleted of ZP3 (125I-ZP1/2) were obtained by antibody affinity purification of ZP3. In competitive binding assays, bands 2 and 3 competed for 125I-ZP3 binding, but band 1 did not interact with enriched 125I-ZP3. None of the membrane fractions competed for 125I-ZP1/2 binding. These results demonstrate that band 2 and band 3 contain sperm components that interact with ZP3 alone and that components in band 1 interact with ZP3 in conjunction with either ZP1 or ZP2. These data indicate that there must be at least 2 unique sperm plasma membrane components that mediate intact sperm interactions with ZP glycoproteins in mouse. Bands 2 and 3 are likely to contain a primary ZP-binding protein because they interacted directly with ZP3, whereas band 1 may contain sperm proteins involved in later interactions with the ZP, perhaps transitional interactions to maintain sperm contact with the ZP during acrosomal exocytosis.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.