Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany.
Proc Natl Acad Sci U S A. 2011 May 31;108(22):9044-8. doi: 10.1073/pnas.1105666108. Epub 2011 May 13.
The human epidermal growth factor receptor (EGFR) is a key representative of tyrosine kinase receptors, ubiquitous actors in cell signaling, proliferation, differentiation, and migration. Although the receptor is well-studied, a central issue remains: How does the compositional diversity and functional diversity of the surrounding membrane modulate receptor function? Reconstituting human EGFR into proteoliposomes of well-defined and controlled lipid compositions represents a minimal synthetic approach to systematically address this question. We show that lipid composition has little effect on ligand-binding properties of the EGFR but rather exerts a profound regulatory effect on kinase domain activation. Here, the ganglioside GM3 but not other related lipids strongly inhibited the autophosphorylation of the EGFR kinase domain. This inhibitory action of GM3 was only seen in liposomes compositionally poised to phase separate into coexisting liquid domains. The inhibition by GM3 was released by either removing the neuraminic acid of the GM3 headgroup or by mutating a membrane proximal lysine of EGFR (K642G). Our results demonstrate that GM3 exhibits the potential to regulate the allosteric structural transition from inactive to a signaling EGFR dimer, by preventing the autophosphorylation of the intracellular kinase domain in response to ligand binding.
人表皮生长因子受体（EGFR）是酪氨酸激酶受体的一个重要代表，是细胞信号转导、增殖、分化和迁移中普遍存在的因素。尽管该受体已经得到了广泛的研究，但一个核心问题仍然存在：周围膜的组成多样性和功能多样性如何调节受体功能？将人 EGFR 重构到具有明确定义和控制的脂质组成的蛋白脂质体中，代表了一种最小的合成方法，可以系统地解决这个问题。我们表明，脂质组成对 EGFR 的配体结合特性几乎没有影响，但对激酶结构域的激活具有深远的调节作用。在这里，神经节苷脂 GM3 而不是其他相关脂质强烈抑制了 EGFR 激酶结构域的自动磷酸化。GM3 的这种抑制作用仅见于组成上能够相分离成共存的液相域的脂质体中。GM3 的抑制作用可以通过去除 GM3 头部的唾液酸或突变 EGFR 的一个膜近端赖氨酸（K642G）来释放。我们的结果表明，GM3 有可能通过阻止配体结合后细胞内激酶结构域的自动磷酸化，来调节从无活性到信号转导 EGFR 二聚体的变构结构转变，从而调节受体功能。
