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Updated: Aug 30, 2026

Medium-throughput Screening Assays for Assessment of Effects on Ca2+-Signaling and Acrosome Reaction in Human Sperm
05:44

Medium-throughput Screening Assays for Assessment of Effects on Ca2+-Signaling and Acrosome Reaction in Human Sperm

Published on: March 1, 2019

Structural requirements for the inhibitory action of the CD9 large extracellular domain in sperm/oocyte binding and

Adrian Higginbottom1, Yuji Takahashi, Laura Bolling

  • 1Department of Neurology, University of Sheffield Medical School, UK.

Biochemical and Biophysical Research Communications
|October 25, 2003
PubMed

Insights

The tetraspanin CD9 protein is crucial for sperm-egg fusion. Researchers identified specific structural requirements of CD9

Area of Science:

  • Reproductive biology
  • Molecular and cell biology

Background:

  • CD9 protein is essential for sperm-oocyte fusion in mice.
  • CD9 functions in cis and trans to regulate this process.
  • The structural basis for CD9's trans inhibitory function is unknown.

Purpose of the Study:

  • To investigate the structural requirements of the CD9 large extracellular domain (LED) for trans inhibition of sperm-oocyte fusion.
  • To determine if human CD9 LED can inhibit mouse sperm-oocyte fusion and binding.

Main Methods:

  • Utilized mouse sperm-oocyte fusion assays.
  • Tested the inhibitory effects of human and mouse CD9 LED.
  • Introduced mutations in the CD9 LED, including disulfide bridge disruption and pentapeptide sequence alteration.

Main Results:

  • Human CD9 LED effectively inhibits mouse sperm-oocyte fusion and binding, similar to mouse CD9 LED.
  • The two conserved disulfide bridges in CD9 LED are critical for its inhibitory function.
  • A specific pentapeptide sequence in the hypervariable region is essential for trans inhibition.

Conclusions:

  • The structural integrity of CD9 LED, particularly its disulfide bridges and a specific pentapeptide region, is vital for its role in regulating sperm-oocyte fusion.
  • These findings provide insights into the molecular mechanisms of gamete fusion and potential targets for fertility regulation.

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