HAP2

HAP2 (hapless 2), also known as GCS1 (generative cell-specific protein 1), is a family of membrane fusion proteins found in the sperm cell of diverse eukaryotes including Toxoplasma, thale cress, and fruit flies. This protein is essential for gamete fusion, and therefore fertilization, in these organisms. It is a domesticated instance of a viral class II fusion protein.^[1]

Male gamete fusion factor
Identifiers
Symbol	HAP2-GCS1
Pfam	PF10699
InterPro	IPR018928
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

References

1. Fédry J, Liu Y, Péhau-Arnaudet G, Pei J, Li W, Tortorici MA, et al. (February 2017). "The Ancient Gamete Fusogen HAP2 Is a Eukaryotic Class II Fusion Protein". Cell. 168 (5): 904–915.e10. doi:10.1016/j.cell.2017.01.024. PMC 5332557. PMID 28235200.