Recovery of various signal transduction molecules in the detergent-resistant membrane microdomain (DRM) fraction suggests the importance of this region in cellular functions. NAP-22 (also called BASP1 or CAP-23) is a neuron-enriched calmodulin-binding protein and one of the major proteins in the DRM fraction of the neuronal cell membrane. Previous studies showed tight binding activity of NAP-22 to acidic membrane lipids and the self-interaction of NAP-22, i.e., oligomerization. In this study, the effect of various phospholipids, lysophospholipids and fatty acids on the oligomerization of NAP-22 was studied through SDS-PAGE after chemical cross-linking and electron microscopic observation. High molecular mass oligomers were detected by SDS-PAGE after incubation in solutions containing over 20 mM NaCl at pH 6.5–8.5, even in the absence of lipid addition, and the addition of Ca²⁺/calmodulin abolished oligomerization. Higher molecular mass oligomer formation after incubation with acidic phospholipids was detected with gradient SDS-PAGE. Much higher mass oligomers were detected in the presence of polyunsaturated fatty acids. Electron microscopic analysis of the samples after SDS treatment showed tangled rope-like structures. Liposome-bound NAP-22 showed small oval or annular structures after cross-linking and SDS treatment. These oligomers were suggested to make the tangled rope-like structures, for annular structures of the same size were observed in the structure. These results suggest the participation of NAP-22 to liquid-liquid phase separation through oligomerization.

耐去污剂的膜微区（DRM）馏分中各种信号转导分子的恢复表明该区域在细胞功能中的重要性。NAP-22（也称为BASP1或CAP-23）是一种富含神经元的钙调蛋白结合蛋白，是神经元细胞膜DRM组分中的主要蛋白之一。先前的研究表明NAP-22与酸性膜脂质的紧密结合活性和NAP-22的自我相互作用（即低聚）。在这项研究中，通过化学交联和电子显微镜观察，通过SDS-PAGE研究了各种磷脂，溶血磷脂和脂肪酸对NAP-22寡聚的影响。在含有超过20 mM NaCl的pH 6.5–8.5的溶液中孵育后，通过SDS-PAGE检测到高分子量的低聚物，²⁺ /钙调蛋白消除了低聚。通过梯度SDS-PAGE检测到与酸性磷脂孵育后，更高分子量的低聚物形成。在多不饱和脂肪酸的存在下，检测到质量更高的低聚物。SDS处理后的样品的电子显微镜分析显示出缠结的绳状结构。交联和SDS处理后，结合脂质体的NAP-22显示出小的椭圆形或环形结构。这些低聚物被建议制造成缠结的绳状结构，因为在结构中观察到相同大小的环形结构。这些结果表明NAP-22通过低聚参与液相-液相分离。