Cell and tissue research
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Cell and tissue research · Sep 2012
ReviewMammalian zona pellucida glycoproteins: structure and function during fertilization.
Zona pellucida (ZP) is a glycoproteinaceous translucent matrix that surrounds the mammalian oocyte and plays a critical role in the accomplishment of fertilization. In humans, it is composed of 4 glycoproteins designated as ZP1, ZP2, ZP3 and ZP4, whereas mouse ZP is composed of ZP1, ZP2 and ZP3 (Zp4 being a pseudogene). In addition to a variable sequence identity of a given zona protein among various species, human ZP1 and ZP4 are paralogs and mature polypeptide chains share an identity of 47%. ⋯ There are subtle differences in the downstream signaling events associated with ZP3 versus ZP1/ZP4-mediated induction of the acrosome reaction. For example, ZP3 but not ZP1/ZP4-mediated induction of the acrosome reaction is dependent on the activation of the Gi protein-coupled receptor. Thus, various studies suggest that, in contrast to mice, in humans more than one zona protein binds to spermatozoa and induces an acrosome reaction.