Missler M, Südhof T C
Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235, USA.
Trends Genet. 1998 Jan;14(1):20-6. doi: 10.1016/S0168-9525(97)01324-3.
The human brain has approximately 10(12) neurons, three orders of magnitude more than there are basepairs in the human genome. Each neuron is connected to other neurons by thousands of synapses, creating a dense network of communicating neurons. Cell-recognition events between neurons at, and outside of synapses, are likely to guide the development and maintenance of the complex network formed by neurons. However, little is known about which proteins are important for neuronal cell recognition. Neurexins, a family of polymorphic cell-surface proteins, might mediate some of these cell recognition events. Thousands of neurexin isoforms are generated from three genes by usage of alternative promoters and alternative splicing. These isoforms are displayed on the neuronal cell surface, with different classes of neurons expressing distinct combinations of isoforms. Neurexins probably have a multitude of ligands, some of which interact only with subsets of neurexin isoforms. This review describes the properties of the neurexin protein family and their potential roles in neuronal cell adhesion and intercellular signaling.
人类大脑约有10（12）个神经元，比人类基因组中的碱基对数量多三个数量级。每个神经元通过数千个突触与其他神经元相连，形成一个密集的神经元通讯网络。突触处及突触外神经元之间的细胞识别事件，可能会引导由神经元形成的复杂网络的发育和维持。然而，对于哪些蛋白质对神经元细胞识别很重要，人们却知之甚少。神经连接蛋白是一类多态性细胞表面蛋白，可能介导其中一些细胞识别事件。通过使用可变启动子和可变剪接，从三个基因中产生了数千种神经连接蛋白异构体。这些异构体展示在神经元细胞表面，不同类型的神经元表达不同的异构体组合。神经连接蛋白可能有多种配体，其中一些仅与神经连接蛋白异构体的子集相互作用。本综述描述了神经连接蛋白家族的特性及其在神经元细胞黏附和细胞间信号传导中的潜在作用。
