Blot Joëlle, Chartrain Isabelle, Roghi Christian, Philippe Michel, Tassan Jean-Pierre
UMR 6061, Centre National de la Recherche Scientifique, IFR 97, Université de Rennes 1, 2 avenue du Professeur Léon Bernard, CS34317, F-35043 Rennes Cedex, France.
Dev Biol. 2002 Jan 15;241(2):327-38. doi: 10.1006/dbio.2001.0525.
We report the characterization of pEg3, a Xenopus protein kinase related to members of the KIN1/PAR-1/MARK family. The founding members of this newly emerging kinase family were shown to be involved in the establishment of cell polarity and both microtubule dynamic and cytoskeleton organization. Sequence analyses suggest that pEg3 and related protein kinases in human, mouse, and Caenorhabditis elegans might constitute a distinct group in this family. pEg3 is encoded by a maternal mRNA, polyadenylated in unfertilized eggs and specifically deadenylated in embryos. In addition to an increase in expression, we have shown that pEg3 is phosphorylated during oocyte maturation. Phosphorylation of pEg3 is cell cycle dependent during Xenopus early embryogenesis and in synchronized cultured XL2 cells. In embryos, the kinase activity of pEg3 is correlated to its phosphorylation state and is maximum during mitosis. Using Xenopus egg extracts we demonstrated that phosphorylation occurs at least in the noncatalytic domain of the kinase, suggesting that this domain might be important for pEg3 function.
我们报道了pEg3的特性，它是一种与KIN1/PAR-1/MARK家族成员相关的非洲爪蟾蛋白激酶。这个新出现的激酶家族的创始成员被证明参与细胞极性的建立以及微管动力学和细胞骨架组织。序列分析表明，人类、小鼠和秀丽隐杆线虫中的pEg3及相关蛋白激酶可能在这个家族中构成一个独特的组。pEg3由母源mRNA编码，在未受精卵中进行多聚腺苷酸化，并在胚胎中特异性地去腺苷酸化。除了表达增加外，我们还表明pEg3在卵母细胞成熟过程中被磷酸化。在非洲爪蟾早期胚胎发育过程中和同步培养的XL2细胞中，pEg3的磷酸化是细胞周期依赖性的。在胚胎中，pEg3的激酶活性与其磷酸化状态相关，并且在有丝分裂期间最高。利用非洲爪蟾卵提取物，我们证明磷酸化至少发生在激酶的非催化结构域，这表明该结构域可能对pEg3的功能很重要。
