Zona pellucida sperm-binding protein 2 is a protein that in humans is encoded by the ZP2 gene.[5][6]

ZP2
Identifiers
AliasesZP2, ZPA, Zp-2, zona pellucida glycoprotein 2, OOMD6
External IDsOMIM: 182888; MGI: 99214; HomoloGene: 48194; GeneCards: ZP2; OMA:ZP2 - orthologs
Orthologs
SpeciesHumanMouse
Entrez
Ensembl
UniProt
RefSeq (mRNA)

NM_001290104
NM_003460
NM_001376231
NM_001376232
NM_001376233

NM_011775
NM_001374631

RefSeq (protein)

NP_003451
NP_001363160
NP_001363161
NP_001363162

NP_035905
NP_001361560

Location (UCSC)Chr 16: 21.2 – 21.21 MbChr 7: 119.73 – 119.74 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

Function

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The zona pellucida is an extracellular matrix that surrounds the oocyte and early embryo. It is composed primarily of three (mouse) or four (human) glycoproteins (ZP1-4) with various functions during fertilization and preimplantation development. The protein encoded by this gene is a structural component of the zona pellucida and functions in secondary binding and penetration of acrosome-reacted spermatozoa. The nascent protein contains a N-terminal signal peptide sequence, a conserved ZP domain, a consensus furin cleavage site, and a C-terminal transmembrane domain. It is hypothesized that furin cleavage results in release of the mature protein from the plasma membrane for subsequent incorporation into the zona pellucida matrix. However, the requirement for furin cleavage in this process remains controversial based on mouse studies.[6]

The sperm-binding domain on the ZP2 protein is necessary in both humans and mice for oocyte-sperm recognition and penetration of the zona pellucida. It is also responsible for the primary block to polyspermy in mammals. The oocyte has cortical granules peripherally located under the cortex that contain a proteolytic protein called ovastacin. After the sperm binds to ZP2, the cortical granules are exocytosed releasing ovastacin into the perivitelline space. Ovastacin cleaves ZP2 at the N terminus, preventing more sperm from binding and penetrating the oocyte, thus hardening the zona pellucida. Ovastacin is only found in oocytes, and is part of the astacin family of metalloendoproteases. Female mice engineered without ovastacin showed that ZP2 was not cleaved after fertilization.[7][8]

3D structure

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The crystal structure of the sperm-binding domain of ZP2 at 0.95 Å resolution (PDB: 5II6​)[9] showed that is shares the same ZP-N fold first identified in structures of ZP3 (PDB: 3D4C, 3D4G, 3EF7, 3NK3, 3NK4​).[10][11] This provided experimental evidence for the suggestion that the N-terminal region of ZP2 consists of three ZP-N repeats [10][12] and revealed that - despite insignificant sequence identity - ZP2 is structurally similar to VERL, the vitelline envelope receptor for egg lysin of the mollusk abalone (PDB: 5II4, 5II5, 5MR2, 5IIC, 5IIA, 5IIB, 5MR3​). This established a link between invertebrate and vertebrate fertilization by suggesting that, despite being separated by 600 million years of evolution, mollusk and human use a common protein fold to interact with sperm.[9]

References

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  1. ^ a b c ENSG00000103310 GRCh38: Ensembl release 89: ENSG00000284588, ENSG00000103310Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000030911Ensembl, May 2017
  3. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. ^ Liang LF, Dean J (Apr 1993). "Conservation of mammalian secondary sperm receptor genes enables the promoter of the human gene to function in mouse oocytes". Dev Biol. 156 (2): 399–408. doi:10.1006/dbio.1993.1087. PMID 8385033.
  6. ^ a b "Entrez Gene: ZP2 zona pellucida glycoprotein 2 (sperm receptor)".
  7. ^ Burkart AD, Xiong B, Baibakov B, Jiménez-Movilla M, Dean J (2012). "Ovastacin, a cortical granule protease, cleaves ZP2 in the zona pellucida to prevent polyspermy". J Cell Biol. 197 (1): 37–44. doi:10.1083/jcb.201112094. PMC 3317803. PMID 22472438.
  8. ^ Avella MA, Baibakov B, Dean J (2014). "A single domain of the ZP2 zona pellucida protein mediates gamete recognition in mice and humans". J Cell Biol. 205 (6): 801–809. doi:10.1083/jcb.201404025. PMC 4068139. PMID 24934154.
  9. ^ a b Raj I, Sadat Al Hosseini H, Dioguardi E, Nishimura K, Han L, Villa A, de Sanctis D, Jovine L (2017). "Structural Basis of Egg Coat-Sperm Recognition at Fertilization". Cell. 169 (7): 1315–1326. doi:10.1016/j.cell.2017.05.033. PMC 5480393. PMID 28622512. PDB: 5II6, 5II4, 5II5, 5MR2, 5IIC, 5IIA, 5IIB, 5MR3
  10. ^ a b Monné M, Han L, Schwend T, Burendahl S, Jovine L (2008). "Crystal structure of the ZP-N domain of ZP3 reveals the core fold of animal egg coats". Nature. 456 (7222): 653–7. Bibcode:2008Natur.456..653M. doi:10.1038/nature07599. hdl:11563/8930. PMID 19052627. S2CID 4430083. PDB: 3D4C, 3D4G, 3EF7
  11. ^ Han L, Monné M, Okumura H, Schwend T, Cherry AL, Flot D, Matsuda T, Jovine L (2010). "Insights into egg coat assembly and egg-sperm interaction from the X-ray structure of full-length ZP3". Cell. 143 (3): 404–15. doi:10.1016/j.cell.2010.09.041. hdl:11563/8931. PMID 20970175. S2CID 18583237. PDB: 3NK3, 3NK4
  12. ^ Callebaut I, Mornon JP, Monget P (2007). "Isolated ZP-N domains constitute the N-terminal extensions of Zona Pellucida proteins". Bioinformatics. 23 (15): 1871–1874. doi:10.1093/bioinformatics/btm265. PMID 17510169.

Further reading

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