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Zona Pellucida
The zona pellucida (plural zonae pellucidae, also egg coat or pellucid zone) is a specialized extracellular matrix that surrounds the plasma membrane of mammalian oocytes. It is a vital constitutive part of the oocyte. The zona pellucida first appears in unilaminar primary oocytes. It is secreted by both the oocyte and the ovarian follicles. The zona pellucida is surrounded by the corona radiata. The corona is composed of cells that care for the egg when it is emitted from the ovary. This structure binds spermatozoa, and is required to initiate the acrosome reaction. In the mouse (the best characterised mammalian system), the zona glycoprotein, ZP3, is responsible for sperm binding, adhering to proteins on the sperm plasma membrane. ZP3 is then involved in the induction of the acrosome reaction, whereby a spermatozoon releases the contents of the acrosomal vesicle. The exact characterisation of what occurs in other species has become more complicated as further zona protein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zona Pellucida-like Domain
The Zona pellucida-like domain (ZP domain / ZP-like domain / ZP module) is a large protein Protein domain, region of about 260 amino acids. It has been recognised in a variety of receptor-like eukaryotic glycoproteins. All of these molecules are mosaic proteins with a large extracellular region composed of various domains, often followed by either a transmembrane region and a very short cytoplasmic region or by a glycosylphosphatidylinositol, GPI-anchor. Functional and crystallographic studies revealed that the "ZP domain" region common to all these proteins is a protein polymerization module that consists of two distinct but structurally related immunoglobulin-like domains, ZP-N and ZP-C. The ZP module is located in the C-terminal portion of the extracellular region and – with the exception of non-polymeric family member endoglin, ENG – contains 8 or 10 conserved Cys residues involved in disulfide bonds. The first 3D structure of a ZP module protein filament, native ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |