中文摘要：

目的通过定位SecA和SecY蛋白来定位Sec分泌系统在变形链球菌上的分布形态。方法用Western blot法检测抗SecA多克隆抗体和SecY多克隆抗体的特异性；胶体金标记免疫电镜观察SecA蛋白和SecY蛋白在变形链球菌GS-5上的分布模式。结果免疫印迹结果表明，抗SecA蛋白的多克隆抗体和抗SecY蛋白的多克隆抗体可分别特异性地识别相对分子质量为95000和47800的抗原。电镜下可见金标记颗粒聚集在变形链球菌GS-5细胞膜上一个微小的区域。结论蛋白SecA和SecY不对称地聚集在变形链球菌细胞膜上一个微小区域，提示Sec分泌系统在变形链球菌细胞膜上呈现单一位点的分布趋势。

英文摘要：

Objective To investigate the distribution pattern of the Secretion complex in Streptococcus mutans by means of the subcellular localization of SecA and SecY. Methods The specificity of anti-SecA antibody and the anti-SecY antibody were examined by Western blot. An indirect postembedding immunogold method was used to determine the subcellular localization of the SecA and SecY in the cytoplasmic membrane of the Streptococcus mutans GS-5. Results Immunoblotting results showed that the anti-SecA antibody and the anti-SecY antibody specifically recognized a single band of about 95 000 and 47 800 respectively. Immunogold electron microscopy revealed a single intense focus of gold particles at a discrete location on the cytoplasmic membrane of the Streptococcus mutans GS-5. Conclusions SecA and SecY clustered to an asymmetric microdomain, which suggests that Sec complex present a uni-site on the cytoplasmic membrane of Streptococcus mutans.