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 region and a very 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.[3][4][5][6][7][8][9][10] The ZP module is located in the C-terminal portion of the extracellular region and – with the exception of non-polymeric family member
ENG[11] – contains 8 or 10 conserved Cys residues involved in disulfide bonds.[5][6][9]
The first 3D structure of a 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, such as human
zona pellucida components
ZP1,
ZP2 and
ZP4 and mollusk
vitelline envelope receptor for
egg lysin (VERL).[5][14][15]
Examples
Humans genes encoding proteins containing this domain include:
^Jovine L, Qi H, Williams Z, Litscher E, Wassarman PM (2002). "The ZP domain is a conserved module for polymerization of extracellular proteins". Nat. Cell Biol. 4 (6): 457–61.
doi:
10.1038/ncb802.
PMID12021773.
S2CID11575790.