Hortsch M, Homer D, Malhotra J D, Chang S, Frankel J, Jefford G, Dubreuil R R
University of Michigan, Department of Anatomy and Cell Biology, Ann Arbor, Michigan 48109-0616, USA.
J Cell Biol. 1998 Jul 13;142(1):251-61. doi: 10.1083/jcb.142.1.251.
Expression of the Drosophila cell adhesion molecule neuroglian in S2 cells leads to cell aggregation and the intracellular recruitment of ankyrin to cell contact sites. We localized the region of neuroglian that interacts with ankyrin and investigated the mechanism that limits this interaction to cell contact sites. Yeast two-hybrid analysis and expression of neuroglian deletion constructs in S2 cells identified a conserved 36-amino acid sequence that is required for ankyrin binding. Mutation of a conserved tyrosine residue within this region reduced ankyrin binding and extracellular adhesion. However, residual recruitment of ankyrin by this mutant neuroglian molecule was still limited to cell contacts, indicating that the lack of ankyrin binding at noncontact sites is not caused by tyrosine phosphorylation. A chimeric molecule, in which the extracellular domain of neuroglian was replaced with the corresponding domain from the adhesion molecule fasciclin II, also selectively recruited ankyrin to cell contacts. Thus, outside-in signaling by neuroglian in S2 cells depends on extracellular adhesion, but does not depend on any unique property of its extracellular domain. We propose that the recruitment of ankyrin to cell contact sites depends on a physical rearrangement of neuroglian in response to cell adhesion, and that ankyrin binding plays a reciprocal role in stabilizing the adhesive interaction.
果蝇细胞黏附分子神经胶质蛋白（neuroglian）在S2细胞中的表达会导致细胞聚集以及锚蛋白（ankyrin）在细胞接触位点的细胞内募集。我们定位了神经胶质蛋白中与锚蛋白相互作用的区域，并研究了将这种相互作用限制在细胞接触位点的机制。酵母双杂交分析以及神经胶质蛋白缺失构建体在S2细胞中的表达确定了一个保守的36个氨基酸的序列，该序列是锚蛋白结合所必需的。该区域内一个保守酪氨酸残基的突变降低了锚蛋白结合和细胞外黏附。然而，这种突变的神经胶质蛋白分子对锚蛋白的残余募集仍局限于细胞接触部位，这表明非接触位点缺乏锚蛋白结合并非由酪氨酸磷酸化引起。一种嵌合分子，其中神经胶质蛋白的细胞外结构域被黏附分子 fasciclin II 的相应结构域所取代，也能选择性地将锚蛋白募集到细胞接触部位。因此，S2细胞中神经胶质蛋白的外向内信号传导依赖于细胞外黏附，但不依赖于其细胞外结构域的任何独特特性。我们提出，锚蛋白募集到细胞接触位点取决于神经胶质蛋白响应细胞黏附的物理重排，并且锚蛋白结合在稳定黏附相互作用中发挥着相互作用的作用。
