Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America.
EM Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America.
PLoS One. 2018 Oct 16;13(10):e0205859. doi: 10.1371/journal.pone.0205859. eCollection 2018.
Densin is a scaffold protein known to associate with key elements of neuronal signaling. The present study examines the distribution of densin at the ultrastructural level in order to reveal potential sites that can support specific interactions of densin. Immunogold electron microscopy on hippocampal cultures shows intense labeling for densin at postsynaptic densities (PSDs), but also some labeling at extrasynaptic plasma membranes of soma and dendrites and endoplasmic reticulum. At the PSD, the median distance of label from the postsynaptic membrane was ~27 nm, with the majority of label (90%) confined within 40 nm from the postsynaptic membrane, indicating predominant localization of densin at the PSD core. Depolarization (90 mM K+ for 2 min) promoted a slight shift of densin label within the PSD complex resulting in 77% of label remaining within 40 nm from the postsynaptic membrane. Densin molecules firmly embedded within the PSD may target a minor pool of CaMKII to substrates at the PSD core.
致密蛋白是一种已知与神经元信号关键元件结合的支架蛋白。本研究在超微结构水平上检查了致密蛋白的分布，以揭示能够支持致密蛋白特定相互作用的潜在部位。对海马培养物的免疫金电子显微镜显示，致密蛋白在突触后密度（PSD）处有强烈标记，但在体和树突的突触外质膜和内质网上也有一些标记。在 PSD 处，标记物与突触后膜的中位数距离约为 27nm，其中 90%的标记物（90%）局限在距突触后膜 40nm 以内，表明致密蛋白主要定位于 PSD 核心。去极化（90mM K+，2 分钟）促进了 PSD 复合物中致密蛋白标记的轻微移位，导致 77%的标记物仍留在距突触后膜 40nm 以内。牢固嵌入 PSD 中的致密蛋白分子可能将少量 CaMKII 靶向到 PSD 核心的底物上。
