Changes in exposed membrane proteins during in vitro capacitation of boar sperm
1Department of Animal Science, University of California, Davis 95616.
Abstract:
Exposed plasma membrane proteins were labeled with 125I before and after incubation of boar sperm under capacitating conditions. Labeled protein profiles were compared to the ability of the sperm to penetrate zona-free hamster ova. Quantitatively, the labeled sperm membrane proteins were primarily low Mr prior to capacitation. The majority of the labeled seminal plasma protein was also low Mr. After capacitation, two new proteins (64,000 Mr and 78,000 Mr) were labeled. Sperm did not exhibit these exposed membrane proteins when incubated under noncapacitating conditions. Appearance of these proteins was not correlated to the percentage of acrosome-reacted sperm. Although the 64,000 Mr protein was not consistently observed, the relative labeling of the 78,000 Mr protein was highly correlated with the ability of sperm to fuse with zona-free hamster ova. The 78,000 Mr protein may be a sperm protein involved in fusion with the egg plasma membrane.
Insights
Researchers identified key sperm membrane proteins involved in fertilization. A 78,000 Mr protein emerged after capacitation and correlated with sperm-egg fusion, suggesting its role in the fertilization process.
Area of Science:
- Reproductive Biology
- Cell Biology
- Biochemistry
Background:
- Sperm capacitation is crucial for fertilization.
- Identifying proteins involved in sperm-egg interaction is vital for understanding reproductive success.
Purpose of the Study:
- To identify changes in exposed boar sperm plasma membrane proteins during capacitation.
- To correlate these protein changes with sperm function, specifically zona-free oocyte penetration and fusion.
Main Methods:
- Boar sperm plasma membrane proteins were labeled with iodine-125 before and after capacitation.
- Labeled protein profiles were analyzed and compared to sperm's ability to penetrate zona-free hamster ova.
Main Results:
- Prior to capacitation, sperm membrane proteins were predominantly low molecular weight (Mr).
- After capacitation, two new proteins (64,000 Mr and 78,000 Mr) became exposed.
- Labeling of the 78,000 Mr protein strongly correlated with sperm-egg fusion, independent of acrosome reaction status.
Conclusions:
- Capacitation induces changes in the exposed sperm plasma membrane proteome.
- A 78,000 Mr protein is a potential key player in mediating sperm-egg fusion during fertilization.
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