ZP3

ZP3 or Zona Pellucida Glycoprotein 3 is a protein that in humans is encoded by the ZP3 gene. It is a vital component of the zona pellucida, which is an extracellular matrix that surrounds the oocyte and early embryo in mammals.

Function

ZP3 is one of the key proteins involved in the process of sperm-egg recognition and binding, which is the initial step in fertilization. It acts as a primary sperm receptor, binding to specific sperm surface proteins and initiating the acrosome reaction. This reaction results in the release of enzymes that allow the sperm to penetrate the zona pellucida and fuse with the egg's membrane.

Structure

The ZP3 protein is a glycoprotein, meaning it is a protein with attached carbohydrate chains. It is composed of approximately 424 amino acids and has a molecular weight of about 47 kDa. The protein has a signal peptide at the N-terminus, which directs it to the secretory pathway, and a ZP domain at the C-terminus, which is involved in polymerization and interaction with sperm.

Clinical Significance

Mutations in the ZP3 gene can lead to infertility due to failure of sperm-egg recognition and binding. This can result in a condition known as oocyte maturation defect, which is characterized by the inability of the oocyte to complete meiosis and mature into a fertilizable egg.

See Also

• Zona pellucida
• Oocyte
• Fertilization
• Sperm
• Acrosome reaction
• Infertility