连接蛋白（Connexin，Cx）。在脊椎动物，由connexin组成的间隙连接信道（Gap Junction channel）介导相邻细胞之间离子、小分子营养物质交换及信号分子传播。哺乳动物发育早期已有多种connexin表达，不同connexin组成的间隙连接信道具有不同通透特征，相邻细胞利用间隙连接介导的细胞间通讯（GJIC,Gap Junction Intercellular Communication）或者不依赖间隙连接信道的途径传递发育信号，调节发育过程中的细胞增殖、迁移和分化。

connexins是一个广泛表达于脊椎动物细胞的蛋白质家族。该家族成员组成的六聚体（connexon）定位于细胞膜上，形成间隙连接信道或半信道（hemi-channel）介导细胞之间、细胞与细胞外基质之间的物质交换。基因组中编码connexin蛋白家族的基因组成connexin基因家族。在人类基因组中已发现21种connexin基因，在小鼠基因组中有20种。这些connexin按其串行相似程度及胞内环长度分为α、β或γ亚组。人类与小鼠connexin基因根据串行同源性配成19对。Connexin基因的结构相对简单，只有两个外显子，一般来说编码区位于第二个外显子，5`-UTR被内含子分隔在两个外显子中，3`-UTR位于第二个外显子中。

Connexins, or gap junction proteins, are a family of structurally related transmembrane proteins that assemble to form vertebrate gap junctions (an entirely different family of proteins, the innexins, form gap junctions in invertebrates). Each gap junction is composed of two hemichannels, or connexons, which are themselves each constructed out of six connexin molecules. Gap junctions are essential for many physiological processes, such as the coordinated depolarization of cardiac muscle, proper embryonic development, and the conducted response in microvasculature. For this reason, mutations in connexin-encoding genes can lead to functional and developmental abnormalities.