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The proacrosin binding protein, sp32, is tyrosine phosphorylated during capacitation of pig sperm

Charlotte Dubé1, Pierre Leclerc, Tadashi Baba

  • 1Département des Sciences Animales, Centre de Recherche en Biologie de la Reproduction, Université Laval, Sainte-Foy, Québec, Canada.

Journal of Andrology
|June 16, 2005
PubMed

Insights

Researchers identified a tyrosine phosphorylated protein (p32) in capacitating sperm as sp32, a protein involved in proacrosin maturation. This finding clarifies sp32's role in sperm capacitation and fertilization.

Area of Science:

  • Reproductive Biology
  • Sperm Physiology
  • Proteomics

Background:

  • Mammalian sperm require capacitation for fertilization.
  • A previously identified Mr 32,000 tyrosine phosphorylated protein (p32) appears during sperm capacitation.
  • The identity and function of p32 in capacitation were unknown.

Purpose of the Study:

  • To identify the protein p32 using proteomic techniques.
  • To elucidate the role of p32 in sperm capacitation.

Main Methods:

  • Western blotting under nonreducing and reducing conditions.
  • Mass spectrometry/mass spectrometry for protein sequencing.
  • Immunoprecipitation and indirect immunofluorescence.
  • Sperm treatment with ionophore to induce acrosome reaction.

Main Results:

  • p32 was identified as sp32, a protein linked to proacrosin maturation.
  • sp32 is tyrosine phosphorylated during capacitation, forming p32.
  • Labeling patterns for sp32 and phosphotyrosine were similar in capacitated sperm.
  • Labeling disappeared from the acrosome after ionophore-induced acrosome reaction.

Conclusions:

  • sp32 is the tyrosine phosphorylated protein p32, playing a role in sperm capacitation.
  • Tyrosine phosphorylation of sp32 is significant for fertilization-related events.
  • Further research will focus on the functional implications of sp32 tyrosine phosphorylation.

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