Izumo sperm-egg fusion protein 1 (Sperm-specific protein izumo) is encoded in humans by the ''IZUMO1''

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

. In mammalian

fertilisation Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a zygote and initiate its development into a new individual organism or of ...

, IZUMO1 binds to its egg receptor counterpart, Juno, to facilitate recognition and fusion of the

gametes A gamete ( ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. The name gamete was introduced by the Ge ...

Function

The sperm-specific protein Izumo, named for a Japanese shrine dedicated to marriage, is essential for sperm-egg plasma membrane binding and fusion. Studies have shown that male Izumo knockout mice are sterile because their sperm are unable to fuse to the oocyte membrane. Izumo -/- mice produced morphologically normal sperm that were able to penetrate the zona pellucida, but could not fuse with to the eggs. In fact, it is necessary to relocate the IZUMO1 to the site of oocyte fusion. In-vitro human experiments have also been conducted, suggesting that Izumo is required for human gamete fusion. Through the use of

Western Blot The western blot (sometimes called the protein immunoblot), or western blotting, is a widely used analytical technique in molecular biology and immunogenetics to detect specific proteins in a sample of tissue homogenate or extract. Besides detect ...

analyses, it has been shown that Izumo is only expressed in the testis and is found on mature spermatozoa. Izumo-1 located on mature spermatozoa that have undergone capacitation binds to its receptor Juno, which is located on the oolemma of eggs. Bianchi E, Doe B, Goulding D, Sanger Mouse Genetics Project, Wright GJ. Juno is the egg Izumo receptor and is essential for mammalian fertilisation. Nature. 2014;508(7497):483-487.

Function

References

Further reading