CABYRY, a novel calcium-binding tyrosine phosphorylation-regulated fibrous sheath protein involved in capacitation
CABYRY, a novel calcium-binding tyrosine phosphorylation-regulated fibrous sheath protein involved in capacitation
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DOI：
10.1006/dbio.2001.0527
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发表时间：
2002-02-15
影响因子：
2.7
通讯作者：
Herr, JC
中科院分区：
文献类型：
--
作者：
Naaby-Hansen, S;Mandal, A;Herr, JC
为了达到受精能力，精子经历了一系列不完全了解的形态和分子成熟过程，称为获能，其中包括蛋白质酪氨酸磷酸化和细胞内钙增加。过度激活的运动性和经历顶体反应的能力是评估获能成功的生理终点。我们报道了一种新的、多态的、睾丸特异的蛋白，命名为钙结合酪氨酸磷酸化调节蛋白(CABYR)的酸性(pI 4.0)86 kDa亚型，在体外获能过程中被酪氨酸磷酸化，并将Ca-45结合在2D凝胶上。在体外获能过程中，CABYR的酸性86 kDa钙结合形式增加，碱性磷酸酶去磷酸化后，与这些酸性形式的钙结合被取消。从人睾丸cDNA文库中克隆了含有两个编码区(CR-A和CR-B)的6个CABYR变异体，其中包括5个具有选择性剪接缺失的变异体。在4个CABYR变异体中，在CR-A的N末端存在一个与PK-A的RII二聚结构域同源的基序。在AAS 197-209的CR-A中发现了一个推测的EF手状基序，而在CR-A中发现了7个潜在的酪氨酸磷酸化样位点，在CR-B中发现了4个潜在的酪氨酸磷酸化样位点。在CR-A和CR-B的N-末端和C-末端鉴定出Pro-X-X-Pro(PXXP)模块。CABYR定位于人类精子鞭毛的主要部分，与纤维鞘相关，这是精子蛋白在获能过程中被磷酸化时获得钙结合能力的第一个证明。(C)2002年埃尔塞维尔科学公司(美国)。
To reach fertilization competence, sperm undergo an incompletely understood series of morphological and molecular maturational processes, termed capacitation, involving, among other processes, protein tyrosine phosphorylation and increased intracellular calcium. Hyperactivated motility and an ability to undergo the acrosome reaction serve as physiological end points to assess successful capacitation. We report here that acidic (pI 4.0) 86-kDa isoforms of a novel, polymorphic, testis-specific protein, designated calcium-binding tyrosine phosphorylation-regulated protein (CABYR), were tyrosine phosphorylated during in vitro capacitation and bound Ca-45 on 2D gels. Acidic 86-kDa calcium-binding forms of CABYR increased during in vitro capacitation, and calcium binding to these acidic forms was abolished by dephosphorylation with alkaline phosphatase. Six variants of CABYR containing two coding regions (CR-A and CR-B) were cloned from human testis cDNA libraries, including five variants with alternative splice deletions. A motif homologous to the RII dimerization domain of PK-A was present in the N-terminus of CR-A in four CABYR variants. A single putative EF handlike motif was noted in CR-A at aas 197-209, while seven potential tyrosine phosphorylation-like sites were noted in CR-A and four in CR-B. Pro-X-X-Pro (PXXP) modules were identified in the N- and C-termini of CR-A and CR-B. CABYR localizes to the principal piece of the human sperm flagellum in association with the fibrous sheath and is the first demonstration of a sperm protein that gains calcium-binding capacity when phosphorylated during capacitation. (C) 2002 Elsevier Science (USA).