Endophilin recruitment drives membrane curvature generation through coincidence detection of GPCR loop interactions and negative lipid charge.
Endophilin recruitment drives membrane curvature generation through coincidence detection of GPCR loop interactions and negative lipid charge.
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DOI：
10.1074/jbc.ra120.016118
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发表时间：
2021-01
期刊：
影响因子：
--
通讯作者：
Baumgart T
中科院分区：
文献类型：
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作者：
Mondal S;Narayan KB;Powers I;Botterbusch S;Baumgart T
在细胞受体的内吞过程中，内亲素起着关键作用，包括产生膜曲率以驱动内化。内啡肽的BIN/Amphiphysin/Rvs结构域和阴离子膜脂质之间的静电相互作用被认为是曲率产生的主要驱动力。然而，内啡肽的SH 3结构域也与各种G蛋白偶联受体（GPCR）的富含脯氨酸的第三胞内环（TIL）相互作用，目前还不清楚这种相互作用是否在胞吞过程中产生膜弯曲中起直接作用。为了检验这一点，我们设计了膜密度为1400个受体/μm2的模型膜，其由来自β1-肾上腺素能受体的共价缀合的TIL区域表示。我们观察到，TIL通过SH 3结构域向由95摩尔%的两性离子脂质组成的膜募集内亲和素。更重要的是，通过TIL募集的内啡肽使囊泡形成管状，并被分选到高度弯曲的膜小管上。这些观察结果表明，除了与阴离子脂质结合之外，还可以通过检测活化的GPCR的TIL来促进内啡肽的细胞膜弯曲和曲率传感活性。此外，我们表明，TIL与阴离子脂质组成的膜静电相互作用。因此，阴离子脂质可以调节TIL/SH 3结构域结合。总体而言，我们的研究结果意味着TIL，带电膜脂质，BAR结构域和SH 3结构域之间的相互作用可能存在于生物系统中，这些组件可以协调调节细胞受体的内化。
Endophilin plays key roles during endocytosis of cellular receptors, including generating membrane curvature to drive internalization. Electrostatic interactions between endophilin’s BIN/Amphiphysin/Rvs domain and anionic membrane lipids have been considered the major driving force in curvature generation. However, the SH3 domain of endophilin also interacts with the proline-rich third intracellular loop (TIL) of various G-protein-coupled receptors (GPCRs), and it is unclear whether this interaction has a direct role in generating membrane curvature during endocytosis. To examine this, we designed model membranes with a membrane density of 1400 receptors per μm2 represented by a covalently conjugated TIL region from the β1-adrenergic receptor. We observed that TIL recruits endophilin to membranes composed of 95 mol% of zwitterionic lipids via the SH3 domain. More importantly, endophilin recruited via TIL tubulates vesicles and gets sorted onto highly curved membrane tubules. These observations indicate that the cellular membrane bending and curvature sensing activities of endophilin can be facilitated through detection of the TIL of activated GPCRs in addition to binding to anionic lipids. Furthermore, we show that TIL electrostatically interacts with membranes composed of anionic lipids. Therefore, anionic lipids can modulate TIL/SH3 domain binding. Overall, our findings imply that an interplay between TIL, charged membrane lipids, BAR domain, and SH3 domain could exist in the biological system and that these components may act in coordination to regulate the internalization of cellular receptors.