Characterization of mouse sperm TMEM190, a small transmembrane protein with the trefoil domain: evidence for co-localization with IZUMO1 and complex formation with other sperm proteins
Characterization of mouse sperm TMEM190, a small transmembrane protein with the trefoil domain: evidence for co-localization with IZUMO1 and complex formation with other sperm proteins
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DOI：
10.1530/rep-10-0391
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发表时间：
2011-04-01
期刊：
影响因子：
3.8
通讯作者：
Primakoff, Paul
中科院分区：
文献类型：
--
作者：
Nishimura, Hitoshi;Gupta, Surabhi;Primakoff, Paul
TMEM190 是一种含有三叶结构域的小型跨膜蛋白，之前通过我们对小鼠精子的蛋白质组学分析鉴定出。 TMEM190 的两个结构特征，“三叶结构域”和“小跨膜蛋白”，使我们推测该蛋白质形成受精过程中所需的蛋白质-蛋白质复合物，并且我们通过生化、细胞学和遗传学方法对 TMEM190 进行了表征。我们在这项研究中表明，小鼠 Tmem190 基因表现出睾丸特异性 mRNA 表达，并且编码的 RNA 被翻译成睾丸生殖细胞和附睾精子尾部中发现的 19-kDa 蛋白质。用蛋白酶K处理细胞表面、亚细胞分级分离和免疫荧光测定均表明小鼠TMEM190是附睾精子尾部的顶体内膜蛋白。在顶体反应过程中，TMEM190部分重新定位到赤道段的表面，在赤道段上发生精子-卵母细胞融合。此外，TMEM190和IZUMO1（一种配子融合所需的免疫球蛋白样蛋白）在顶体反应前后共定位于小鼠精子中。然而，TMEM190 的免疫沉淀物含有几种精子蛋白，但不包括 IZUMO1。这些发现表明，包含 TMEM190 的小鼠精子蛋白复合物在精子-卵母细胞融合中发挥间接作用。如果有的话，这些作用可能是可有可无的，因为 Tmem190 缺失的雄性小鼠通常具有生育能力。复制（2011）141 437-451
TMEM190, a small transmembrane protein containing the trefoil domain, was previously identified by our proteomic analysis of mouse sperm. Two structural features of TMEM190, 'trefoil domain' and 'small transmembrane protein', led us to hypothesize that this protein forms a protein-protein complex required during fertilization, and we characterized TMEM190 by biochemical, cytological, and genetic approaches. We showed in this study that the mouse Tmem190 gene exhibits testis-specific mRNA expression and that the encoded RNA is translated into a 19-kDa protein found in both testicular germ cells and cauda epididymal sperm. Treatment of the cell surface with proteinase K, subcellular fractionation, and immunofluorescence assay all revealed that mouse TMEM190 is an inner-acrosomal membrane protein of cauda epididymal sperm. During the acrosome reaction, TMEM190 partly relocated onto the surface of the equatorial segment, on which sperm-oocyte fusion occurs. Moreover, TMEM190 and IZUMO1, which is an immunoglobulin-like protein required for gamete fusion, co-localized in mouse sperm both before and after the acrosome reaction. However, immunoprecipitates of TMEM190 contained several sperm proteins, but did not include IZUMO1. These findings suggest that a mouse sperm protein complex(es) including TMEM190 plays an indirect role(s) in sperm-oocyte fusion. The role(s), if any, is probably dispensable since Tmem190-null male mice were normally fertile. Reproduction (2011) 141 437-451