Quill T A, Ren D, Clapham D E, Garbers D L
Cecil H. and Ida Green Center for Reproductive Biology Sciences, Department of Pharmacology, and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.
Proc Natl Acad Sci U S A. 2001 Oct 23;98(22):12527-31. doi: 10.1073/pnas.221454998.
Calcium ions play a primary role in the regulation of sperm cell behavior. We report finding a voltage-gated ion channel (CatSper2) that is expressed in male germ cells but not in other cells. The putative channel contains 6 transmembrane segments, making it more similar to the voltage-gated potassium channels, but the ion selectivity pore domain sequence resembles that of a Ca(v) channel. The mRNA is expressed during the meiotic or postmeiotic stages of spermatogenesis, and the protein is localized to the sperm flagellum, suggesting a role in the regulation of sperm motility. The mRNA for the channel is present in mouse, rat, and human sperm cells, and the gene is found on chromosome 2 E5-F1 in the mouse and 15q13 in the human. Recently, another voltage-gated channel (CatSper) that has features similar to the one reported here was discovered. It also is expressed within the flagellum and is required for normal fertility of mice. However, expression of CatSper2 alone or coexpression with CatSper in cultured cells, or attempts to coimmunoprecipitate the two proteins from germ cells failed to demonstrate that these two unique but similar alpha-like subunits form either a homo- or heterotetramer. It is possible, therefore, that two independent alpha subunits, different from other known voltage-gated channels, regulate sperm motility.
钙离子在精子细胞行为的调节中起主要作用。我们报告发现一种电压门控离子通道（CatSper2），它在雄性生殖细胞中表达，但在其他细胞中不表达。该推定通道包含6个跨膜片段，使其更类似于电压门控钾通道，但离子选择性孔域序列类似于Ca(v)通道。该mRNA在精子发生的减数分裂或减数分裂后阶段表达，且该蛋白质定位于精子鞭毛，提示其在精子运动调节中发挥作用。该通道的mRNA存在于小鼠、大鼠和人类精子细胞中，该基因在小鼠中位于2号染色体E5-F1区域，在人类中位于15号染色体q13区域。最近，发现了另一种与本文报道的通道具有相似特征的电压门控通道（CatSper）。它也在鞭毛内表达，是小鼠正常生育所必需的。然而，单独表达CatSper2或在培养细胞中与CatSper共表达，或尝试从生殖细胞中共免疫沉淀这两种蛋白质，均未能证明这两个独特但相似的α样亚基形成同四聚体或异四聚体。因此，有可能两个独立的α亚基不同于其他已知的电压门控通道，调节精子运动。
