Stauffer K A, Unwin N
Medical Research Council, Laboratory of Molecular Biology, Cambridge, UK.
Semin Cell Biol. 1992 Feb;3(1):17-20. doi: 10.1016/s1043-4682(10)80004-2.
Gap junctions are regions of contact between adjacent cells, consisting of arrays of channels linking the cell interiors. The channels are formed by polypeptides called connexins; the amino acid sequences of many different connexins are known, and they are thought to resemble each other closely in tertiary and quarternary structure. Single channels have recently been isolated and purified, and earlier evidence has been confirmed showing that they consist of six identical subunits arranged around the central pore. Gap junction channels are known to open and close in response to changes in ligand concentrations and electrical potential; in this respect they are very similar to ligand-gated ion channels which act as receptors in the membranes of excitable cells. The similarity is shown to extend to structural features such as the amino acid residues lining the pore, and perhaps the location of the actual gate.
间隙连接是相邻细胞之间的接触区域，由连接细胞内部的通道阵列组成。这些通道由称为连接蛋白的多肽形成；许多不同连接蛋白的氨基酸序列已为人所知，并且人们认为它们在三级和四级结构上彼此非常相似。最近已分离和纯化出单通道，并且早期的证据得到了证实，表明它们由围绕中心孔排列的六个相同亚基组成。已知间隙连接通道会响应配体浓度和电势的变化而打开和关闭；在这方面，它们与作为可兴奋细胞膜中受体的配体门控离子通道非常相似。这种相似性延伸到诸如孔内衬里的氨基酸残基等结构特征，也许还有实际门的位置。
