Zona pellucida-like domain | |||||||||
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Identifiers | |||||||||
Symbol | Zona_pellucida | ||||||||
Pfam | PF00100 | ||||||||
InterPro | IPR001507 | ||||||||
SMART | SM00241 | ||||||||
PROSITE | PDOC00577 | ||||||||
Membranome | 146 | ||||||||
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The zona pellucida-like domain (ZP domain / ZP-like domain / ZP module) [1] [2] is a large protein region of about 260 amino acids. It has been recognised in a variety of receptor-like eukaryotic glycoproteins. [1] All of these molecules are mosaic proteins with a large extracellular region composed of various domains, often followed by either a transmembrane domain and a short cytoplasmic region or by a GPI-anchor. [2]
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, separated by an interdomain linker (ITD). [3] [4] [5] [6] [7] [8] [9] The ZP module is located in the C-terminal portion of the extracellular region and – with the exception of non-polymeric family member ENG [10] – contains 8 or 10 conserved Cys residues involved in disulfide bonds. [4] [5] [8] The ZP-C domain contains a EHP/IHP motif that controls polymerization. [11]
The first 3D structure of a homopolymeric ZP module protein filament, native human uromodulin (UMOD), was determined by cryo-EM. [12] [13]
Additional copies of isolated ZP-N domains are found in the N-terminal region of egg coat protein subunits involved in fertilization in both vertebrates and invertebrates, with the human zona pellucida components ZP1, ZP2 and ZP4 being the best understood. [4] [14] The mollusc "vitelline envelope receptor for egg lysin" (VERL, Q8WR62 ) is found in the vitelline envelope of mollusc eggs and consists of 22 VERL repeats followed by a ZP module. Structural work from 2017 demonstrated that VERL repeats are also ZP-N domains. [15]
Humans genes encoding proteins containing this domain include: