Brümmendorf T, Rathjen F G
Max-Planck-Institut für Entwicklungsbiologie, Tübingen, F.R.G.
J Neurochem. 1993 Oct;61(4):1207-19. doi: 10.1111/j.1471-4159.1993.tb13611.x.
The L1- and F11-like axonal glycoproteins, implicated in neurite outgrowth and fasciculation, are members of the Ig superfamily comprising multiple fibronectin type III-like domains. Their Ig-like and fibronectin type III-related domains are likely to be composed of seven beta-strands arranged in two opposing beta-sheets of highly similar topology. Whereas the F11-like molecules lack a transmembrane sequence and are anchored in the plasma membrane by a glycosylphosphatidylinositol, the L1-like molecules comprise cytoplasmic domains with highly conserved sequence motifs. Most of the latter proteins occur in different isoforms generated by alternative pre-mRNA splicing, which has not been documented for molecules of the F11 subgroup. L1-like proteins undergo heterophilic as well as homophilic interactions, whereas only the former mode of binding was observed for F11-like proteins. Evidence is accumulating that these Ig superfamily molecules with fibronectin type III-like domains are interacting in a complex manner with each other and molecules of the extracellular matrix. Investigations assigning structure to function reveal that their individual extracellular domains serve distinct binding activities. Recent studies also suggest that L1 and NCAM are implicated in the transduction of transmembrane signals.
与神经突生长和束状化有关的L1样和F11样轴突糖蛋白是免疫球蛋白超家族的成员，该家族包含多个纤连蛋白III型样结构域。它们的免疫球蛋白样和纤连蛋白III型相关结构域可能由七条β链组成，排列在两个拓扑结构高度相似的反向β折叠片中。F11样分子缺乏跨膜序列，通过糖基磷脂酰肌醇锚定在质膜上，而L1样分子包含具有高度保守序列基序的细胞质结构域。后一种蛋白质中的大多数以可变前体mRNA剪接产生的不同异构体形式存在，F11亚组的分子尚未有相关记录。L1样蛋白会发生异嗜性以及同嗜性相互作用，而F11样蛋白仅观察到前一种结合模式。越来越多的证据表明，这些具有纤连蛋白III型样结构域的免疫球蛋白超家族分子彼此之间以及与细胞外基质分子以复杂的方式相互作用。将结构与功能对应起来的研究表明，它们各自的细胞外结构域具有不同的结合活性。最近的研究还表明，L1和神经细胞黏附分子（NCAM）与跨膜信号转导有关。
