Topinka J R, Bredt D S
Department of Physiology, University of California at San Francisco, 94143, USA.
Neuron. 1998 Jan;20(1):125-34. doi: 10.1016/s0896-6273(00)80440-7.
Ion channels and associated signal transduction cascades are clustered at excitatory synapses by PSD-95 and related PDZ-containing proteins. Mechanisms that target PSD-95 to synaptic membranes, however, are unknown. Here, PSD-95 is shown to partition as an integral membrane protein in brain homogenates. Metabolic labeling of brain slices or cultured cells demonstrates that PSD-95 is modified by thioester-linked palmitate, a long chain fatty acid that targets proteins to cell membranes. In fact, PSD-95 is a major palmitoylated protein in intact cells, and palmitoylated PSD-95 partitions exclusively with cell membranes. Mutagenesis indicates that palmitoylation of PSD-95 occurs on conserved N-terminal cysteines 3 and 5. Palmitoylation-deficient mutants of PSD-95 do not partition as integral membrane proteins and do not participate in PDZ-ion channel interactions in vivo. This work identifies palmitoylation as a critical regulatory mechanism for receptor interactions with PSD-95.
离子通道及相关信号转导级联反应通过PSD-95及相关含PDZ结构域的蛋白质聚集在兴奋性突触处。然而，将PSD-95靶向突触膜的机制尚不清楚。在此，PSD-95在脑匀浆中表现为整合膜蛋白。对脑切片或培养细胞进行代谢标记表明，PSD-95被硫酯连接的棕榈酸修饰，棕榈酸是一种将蛋白质靶向细胞膜的长链脂肪酸。事实上，PSD-95是完整细胞中主要的棕榈酰化蛋白，且棕榈酰化的PSD-95仅与细胞膜共分配。诱变表明，PSD-95的棕榈酰化发生在保守的N端半胱氨酸3和5上。PSD-95的棕榈酰化缺陷突变体不会作为整合膜蛋白进行分配，也不会在体内参与PDZ-离子通道相互作用。这项研究将棕榈酰化确定为受体与PSD-95相互作用的关键调节机制。
