The Proacrosin Binding Protein, sp32, Is Tyrosine Phosphorylated During Capacitation of Pig Sperm
- 8 July 2005
- journal article
- Published by Wiley in Journal of Andrology
- Vol. 26 (4), 519-528
- https://doi.org/10.2164/jandrol.04163
Abstract
Mammalian sperm must undergo capacitation, a preparation period in the female reproductive tract or in vitro, in order to fertilize. We have previously described a Mr 32 000 tyrosine phosphorylated protein, "p32," that appears in pig sperm during capacitation. The identity of p32 remains unknown; if and how it is involved during capacitation is not understood. The objective of the present study was to identify p32 by proteomic techniques. Western blotting of proteins separated successively under nonreducing and then reducing conditions showed the appearance of the tyrosine phosphorylated p32 only when sperm were incubated in capacitating conditions. The spot was sequenced by mass spectrometry/mass spectrometry and identified as "sp32," a protein implicated in proacrosin maturation. The same membranes probed with anti-sp32 antibody demonstrated that sp32 is present in both noncapacitating and capacitating conditions and revealed exactly the same spot as p32. Immunoprecipitation with either anti-phosphotyrosine or anti-sp32 antibody corroborated these results. Indirect immunofluorescence with anti-phosphotyrosine antibody or anti-sp32 antibody show similar labeling of capacitated sperm, supporting the hypothesis that p32 is a tyrosine phosphorylated form of sp32. After ionophore treatment to induce the acrosome reaction, anti-sp32 and anti-phosphotyrosine labeling on the acrosome disappeared. These results demonstrate that sp32, a (pro)acrosin binding protein, is the p32, a tyrosine phosphorylated protein related to capacitation. We will now focus on the significance of tyrosine phosphorylation on sp32 function during fertilization-related events.Keywords
This publication has 41 references indexed in Scilit:
- A unique mechanism for cyclic adenosine 3′,5′‐monophosphate‐induced increase of 32‐kDa tyrosine‐phosphorylated protein in boar spermatozoaMolecular Reproduction and Development, 2004
- Molecular characterization of the 32 kDa boar sperm proteaseMolecular Reproduction and Development, 2004
- ProteomicsAnnual Review of Biochemistry, 2003
- Identification of the major tyrosine phosphorylated protein of capacitated hamster spermatozoa as a homologue of mammalian sperm a kinase anchoring proteinMolecular Reproduction and Development, 2002
- Identification of capacitation-associated phosphoproteins in porcine sperm electroporated with ATP-?-32PMolecular Reproduction and Development, 1999
- Protein—Protein Interactions Controlling Acrosin Release and Solubilization during the Boar Sperm Acrosome ReactionBiology of Reproduction, 1993
- Relationship between molecular conversions of acrosin and the progression of exocytosis in the calcium ionophore-induced acrosome reactionBiochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1993
- Demonstration of a boar testicular protein band that is immunoreactive to proacrosin and proacrosin binding protein antibodiesBiochemical and Biophysical Research Communications, 1992
- Proacrosin activation in the presence of a 32-kDa protein from boar spermatozoaBiochemical and Biophysical Research Communications, 1989
- Fertilizing Capacity of Spermatozoa deposited into the Fallopian TubesNature, 1951