The activation mechanism of the ErbB family of receptors is of considerable medical interest as they are linked to a number of human cancers, including an aggressive form of breast cancer. In the rat analogue of the human ErbB2 receptor, referred to as Neu, a point mutation in the transmembrane domain (V664E) has been shown to trigger oncogenic transformation. While the structural impact of this mutation has been widely studied in the past to yield models for the active state of the Neu receptor, little is known about the impact of cholesterol on its structure. Given previous reports of the influence of cholesterol on other receptor tyrosine kinases (RTKs), as well as the modulation of lipid composition in cancer cells, we wished to investigate how cholesterol content impacts the structure of the Neu transmembrane domain. We utilized high-resolution magic angle spinning solid-state NMR to measure 13C-13C coupling of selectively labelled probe residues in the Neu transmembrane domain in lipid bilayers containing cholesterol. We observe inter-helical coupling between residues that support helix-helix interactions on both dimerization motifs reported in the literature (A661-XXX-G665 and I659-XXX-V663). We further explore how changes in cholesterol concentration alter transmembrane domain interactions and the properties and mechanics of the bilayer. We interpret our results in light of previous studies relating RTK activity to cholesterol enrichment and/or depletion, and propose a novel model to explain our data that includes the recognition and binding of cholesterol by the Neu transmembrane domain through a putative cholesterol-recognition/interaction amino acid consensus sequence.

中文翻译：

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通过膜流动性和胆固醇调节Neu受体酪氨酸激酶中跨膜域相互作用。

ErbB受体家族的激活机制具有重要的医学意义，因为它们与许多人类癌症相关，包括侵袭性乳腺癌。在人类ErbB2受体的大鼠类似物（称为Neu）中，跨膜结构域（V664E）中的点突变已显示触发致癌转化。尽管过去已经对该突变的结构影响进行了广泛研究，以产生Neu受体活性状态的模型，但对胆固醇对其结构的影响知之甚少。鉴于先前关于胆固醇对其他受体酪氨酸激酶（RTK）的影响以及癌细胞中脂质组成的调节的报道，我们希望研究胆固醇含量如何影响Neu跨膜结构域的结构。我们利用高分辨率魔角旋转固态NMR来测量13C-13C偶联，该偶联在含有胆固醇的脂质双层中的Neu跨膜结构域中选择性标记的探针残基。我们观察到在文献（A661-XXX-G665和I659-XXX-V663）中报道的两个二聚化基序上支持螺旋-螺旋相互作用的残基之间的螺旋间偶联。我们进一步探索胆固醇浓度的变化如何改变跨膜结构域相互作用以及双层的性质和力学。我们根据先前有关RTK活性与胆固醇富集和/或消耗的研究来解释我们的结果，