Molecular characterization of a thrombospondin-related anonymous protein homologue in Neospora caninum
Molecular characterization of a thrombospondin-related anonymous protein homologue in Neospora caninum
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DOI：
10.1016/s0166-6851(99)00228-5
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发表时间：
2000-03-15
影响因子：
1.5
通讯作者：
Sibley, LD
中科院分区：
文献类型：
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作者：
Lovett, JL;Howe, DK;Sibley, LD
血小板反应蛋白相关匿名蛋白 (TRAP) 家族成员参与顶复门寄生虫对宿主细胞的附着和侵袭。对犬新孢子虫菌株 Nc-1 (NcMIC2) 中的 TRAP 同源物进行克隆、测序，发现其在氨基酸水平上与弓形虫 MIC2 (TgMIC2) 61% 相同（75% 相似）。与 TgMIC2 类似，NcMIC2 的预测氨基酸序列包含 1 个整联蛋白样结构域（I 或 A 结构域）、5 个血小板反应蛋白 (TSP) 重复序列、一个假定的跨膜跨越区和细胞内 C 末端，并通过冷冻免疫电子显微镜定位于微线体。 NcMIC2 的分泌是温度依赖性的，并且在 25 摄氏度或更高温度下诱导。释放到培养基中的 NcMIC2 的分泌形式被发现经过蛋白水解加工，因此它缺乏 C 末端结构域。 NcMIC2 的分泌受钙调节，因为几种提高细胞内钙水平的药物被证明可以促进 NcMIC2 分泌并螯合 [Ca2+](i) 消除释放。作为不断增长的 apicomplexan TRAP 蛋白家族的一员，NcMIC2 可能在犬新孢子虫附着和侵入宿主细胞中发挥重要作用。 (C) 2000 Elsevier Science B.V. 保留所有权利。
Thrombospondin-related anonymous protein (TRAP) family members participate in attachment and invasion of host cells by apicomplexan parasites. A TRAP homologue in Neospora caninum strain Nc-l (NcMIC2) was cloned, sequenced and found to be 61% identical (75% similar) at the amino acid level to Toxoplasma gondii MIC2 (TgMIC2). Similar to TgMIC2, the predicted amino acid sequence of NcMIC2 contains one integrin-like domain (I or A domain), five thrombospondin (TSP) repeats, a putative transmembrane spanning region and intracellular C-terminus, and was localized to micronemes by cryo-immunoelectron microscopy. The secretion of NcMIC2 was temperature dependent and was induced at or above 25 degrees C. The secreted form of NcMIC2 released into the medium was found to be proteolytically processed such that it lacked the C-terminal domain. Secretion of NcMIC2 was regulated by calcium, since several agents which raise intracellular calcium levels were shown to promote NcMIC2 secretion and chelation of [Ca2+](i) abrogated release. As a member of the growing family of apicomplexan TRAP proteins, NcMIC2 may play an important role in attachment and invasion by N. caninum into host cells. (C) 2000 Elsevier Science B.V. All rights reserved.