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XB-ART-18404
J Biol Chem 1996 Mar 29;27113:7253-6.
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Hyperphosphorylation of nucleoplasmin facilitates Xenopus sperm decondensation at fertilization.

Leno GH , Mills AD , Philpott A , Laskey RA .


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Previous studies showed that the nuclear phosphoprotein nucleoplasmin performs the first stage of chromatin decondensation of Xenopus sperm at fertilization. It binds and removes sperm basic proteins replacing them with histones. We now show that this activity depends upon the massive hyperphosphorylation of nucleoplasmin that occurs when oocytes mature into eggs. Egg extracts or purified hyperphosphorylated egg nucleoplasmin decondense sperm chromatin and remove sperm basic proteins much faster than oocyte extracts or hypophosphorylated oocyte nucleoplasmin. Furthermore, dephosphorylation of egg nucleoplasmin slows sperm decondensation and prevents basic protein removal from sperm chromatin. We conclude that hyperphosphorylation of nucleoplasmin is used to modulate the rapid changes in chromatin structure that accompany early development in Xenopus.

???displayArticle.pubmedLink??? 8631735
???displayArticle.link??? J Biol Chem
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Species referenced: Xenopus
Genes referenced: npm1