Ichtchenko K, Nguyen T, Südhof T C
Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235, USA.
J Biol Chem. 1996 Feb 2;271(5):2676-82. doi: 10.1074/jbc.271.5.2676.
Neuroligin 1 is a neuronal cell surface protein that binds to a subset of neurexins, polymorphic cell surface proteins that are also localized on neurons (Ichtchenko, K., Hata, Y., Nguyen, T., Ullrich, B., Missler, M., Moomaw, C., and Südhof, T. C. (1995) Cell 81, 435-443). We now describe two novel neuroligins called neuroligins 2 and 3 that are similar in structure and sequence to neuroligin 1. All neuroligins contain an N-terminal hydrophobic sequence with the characteristics of a cleaved signal peptide followed by a large esterase homology domain, a highly conserved single transmembrane region, and a short cytoplasmic domain. The three neuroligins are alternatively spliced at the same position and are expressed at high levels only in brain. Binding studies demonstrate that all three neuroligins bind to beta-neurexins both as native brain proteins and as recombinant proteins. Tight binding of the three neuroligins to beta-neurexins is observed only for beta-neurexins lacking an insert in splice site 4. Thus, neuroligins constitute a multigene family of brain-specific proteins with distinct isoforms that may have overlapping functions in mediating recognition processes between neurons.
神经连接蛋白1是一种神经元细胞表面蛋白，它能与一组神经配蛋白结合，神经配蛋白是同样定位于神经元上的多态性细胞表面蛋白（伊琴琴科，K.，羽田，Y.，阮，T.，乌尔里希，B.，米斯勒，M.，穆莫，C.，和苏多霍夫，T.C.（1995年）《细胞》81卷，435 - 443页）。我们现在描述两种新的神经连接蛋白，称为神经连接蛋白2和神经连接蛋白3，它们在结构和序列上与神经连接蛋白1相似。所有神经连接蛋白都含有一个N端疏水序列，具有切割信号肽的特征，随后是一个大的酯酶同源结构域、一个高度保守的单跨膜区域和一个短的胞质结构域。这三种神经连接蛋白在同一位置进行可变剪接，并且仅在脑中高水平表达。结合研究表明，这三种神经连接蛋白作为天然脑蛋白和重组蛋白都能与β - 神经配蛋白结合。仅在剪接位点4缺乏插入片段的β - 神经配蛋白中观察到这三种神经连接蛋白与β - 神经配蛋白的紧密结合。因此，神经连接蛋白构成了一个脑特异性蛋白的多基因家族，具有不同的异构体，可能在介导神经元之间的识别过程中具有重叠功能。
