Differential phosphorylation of the gap junction protein connexin43 in junctional communication-competent and -deficient cell lines.
Differential phosphorylation of the gap junction protein connexin43 in junctional communication-competent and -deficient cell lines.
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DOI：
10.1083/jcb.111.5.2077
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发表时间：
1990-11
期刊：
影响因子：
--
通讯作者：
Goodenough DA
中科院分区：
文献类型：
--
作者：
Musil LS;Cunningham BA;Edelman GM;Goodenough DA
连接蛋白43是高度同源的间隙连接蛋白家族的成员。我们已经研究了连接蛋白单体如何组装成功能性间隙连接斑块，通过检查连接蛋白43在细胞类型中的生物合成，这些细胞类型在形成功能性间隙连接的能力上有很大差异。使用代谢性放射性标记和免疫沉淀的组合，我们已经表明，连接蛋白43在间隙连接通讯活性细胞中合成为42 kD的蛋白质，其通过翻译后添加磷酸盐有效地转化为约46 kD的物质（连接蛋白43-P2）。令人惊讶的是，某些严重缺乏间隙连接通讯和已知细胞间粘附分子的细胞系（S180和L929细胞）也表达42-kD连接蛋白43。然而，这些通讯缺陷细胞系中的连接蛋白43没有磷酸化为P2形式。通过用编码细胞-细胞粘附分子L-CAM的cDNA转染将S180细胞转化为具有通信能力的表型，诱导连接蛋白43磷酸化为P2形式;相反，阻断通常具有通信能力的细胞中的连接通信抑制连接蛋白43-P2的形成。免疫组织化学定位研究表明，只有通信能力的细胞积累的缝隙连接蛋白43可见的缝隙连接斑块。总之，这些结果建立了细胞将连接蛋白43加工成P2形式和产生功能性间隙连接的能力之间的强相关性。因此，连接蛋白43磷酸化可能在间隙连接组装和/或活性中发挥功能性作用。
Connexin43 is a member of the highly homologous connexin family of gap junction proteins. We have studied how connexin monomers are assembled into functional gap junction plaques by examining the biosynthesis of connexin43 in cell types that differ greatly in their ability to form functional gap junctions. Using a combination of metabolic radiolabeling and immunoprecipitation, we have shown that connexin43 is synthesized in gap junctional communication-competent cells as a 42-kD protein that is efficiently converted to a approximately 46-kD species (connexin43-P2) by the posttranslational addition of phosphate. Surprisingly, certain cell lines severely deficient in gap junctional communication and known cell-cell adhesion molecules (S180 and L929 cells) also expressed 42-kD connexin43. Connexin43 in these communication-deficient cell lines was not, however, phosphorylated to the P2 form. Conversion of S180 cells to a communication-competent phenotype by transfection with a cDNA encoding the cell-cell adhesion molecule L-CAM induced phosphorylation of connexin43 to the P2 form; conversely, blocking junctional communication in ordinarily communication-competent cells inhibited connexin43-P2 formation. Immunohistochemical localization studies indicated that only communication-competent cells accumulated connexin43 in visible gap junction plaques. Together, these results establish a strong correlation between the ability of cells to process connexin43 to the P2 form and to produce functional gap junctions. Connexin43 phosphorylation may therefore play a functional role in gap junction assembly and/or activity.