Avian IgY is selectively incorporated into the egg yolks of oocytes by discriminating Fc amino acid residues located on the Cυ3/Cυ4 interface
Avian IgY is selectively incorporated into the egg yolks of oocytes by discriminating Fc amino acid residues located on the Cυ3/Cυ4 interface
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DOI：
10.1016/j.dci.2012.12.003
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发表时间：
2013-04-01
影响因子：
2.9
通讯作者：
Horio, Fumihiko
中科院分区：
文献类型：
--
作者：
Murai, Atsushi;Murota, Rie;Horio, Fumihiko
在鸟类中，母体IgY被选择性地掺入成熟卵母细胞的蛋黄中，但受体介导的摄取的相关性尚不清楚。在这里，我们调查的关键氨基酸残基的卵黄运输所需的进行突变分析的选定的残基位于沿着的C upp 3和C upp 4结构域的鸡IgY。合成了重组野生型IgY-Fc（WT）及其突变体，并测定了其在鹌鹑蛋黄中的摄取。在17个氨基酸残基位于C upp 3/C upp 4接口，在C upp 3结构域的Y363丙氨酸取代废除IgY-Fc摄取到蛋黄。Y363位氨基酸的综合置换表明，为了保持较高的转运能力，Y363位氨基酸残基需要配置芳香族氨基酸。通过用丙氨酸取代C upp 3结构域处的N407的N-连接的碳水化合物链的去糖基化也引起IgY-Fc摄取的显著降低。注射WT和Y363 A突变体的卵巢卵泡中的显微镜检测显示，WT集中地积聚在卵黄颗粒中，而Y363 A突变体几乎不积聚在卵黄颗粒中，但它已经渗透到颗粒细胞层中，这表明干扰Y363 A突变体渗透的主要障碍在于颗粒细胞层的内部。IgY高效转运所需的重要氨基酸残基的鉴定增强了我们对IgY通过卵泡中特异性IgY受体转运的分子机制的理解。(C)2013爱思唯尔有限公司保留所有权利。
In avian species, maternal IgY is selectively incorporated into the egg yolks of maturing oocytes, but the relevance of receptor-mediated uptake is unclear. Here we investigated the critical amino acid residues of IgY required for egg yolk transport by conducting mutational analyses of selected residues located along the C upsilon 3 and C upsilon 4 domains of chicken IgY. Recombinant wild-type IgY-Fc (WT) and its mutants were synthesized, and their uptakes into the egg yolks of quail were determined. Among the 17 amino-acid residues located on the C upsilon 3/C upsilon 4 interface, the substitution of Y363 at the C upsilon 3 domain to alanine abolished the IgY-Fc uptake into egg yolks. The comprehensive substitution of Y363 with other amino acids revealed that the residue at 363 needs to be allocated with aromatic amino acids to maintain the high transport ability. The deglycosylation of the N-linked carbohydrate chain by substituting N407 at the C upsilon 3 domain with alanine also caused a marked reduction of IgY-Fc uptake. The microscopic detection of the injected WT and Y363A mutant in ovarian follicles showed that the WT was concentrically accumulated in yolk granules, whereas the Y363A mutant was hardly accumulated in yolk granules, but it had infiltrated into the granulosa cell layer, suggesting that a major hurdle disturbing the infiltration of the Y363A mutant lies on the inside of the granulosa cell layer. The identification of important amino acid residues required for efficient IgY transport enhances our understanding of the molecular mechanisms underlying IgY transport through a specific IgY receptor in ovarian follicles. (C) 2013 Elsevier Ltd. All rights reserved.