Craven S E, El-Husseini A E, Bredt D S
Department of Physiology and Program in Neuroscience, University of California, San Francisco 94143-0444, USA.
Neuron. 1999 Mar;22(3):497-509. doi: 10.1016/s0896-6273(00)80705-9.
During synaptic development, proteins aggregate at specialized pre- and postsynaptic structures. Mechanisms that mediate protein clustering at these sites remain unknown. To investigate this process, we analyzed synaptic targeting of a postsynaptic density protein, PSD-95, by expressing green fluorescent protein- (GFP-) tagged PSD-95 in cultured hippocampal neurons. We find that postsynaptic clustering relies on three elements of PSD-95: N-terminal palmitoylation, the first two PDZ domains, and a C-terminal targeting motif. In contrast, disruptions of PDZ3, SH3, or guanylate kinase (GK) domains do not affect synaptic targeting. Palmitoylation is sufficient to target the diffusely expressed SAP-97 to synapses, and palmitoylation cannot be replaced with alternative membrane association motifs, suggesting that a specialized synaptic lipid environment mediates postsynaptic clustering. The requirements for PDZ domains and a C-terminal domain of PSD-95 indicate that protein-protein interactions cooperate with lipid interactions in synaptic targeting.
在突触发育过程中，蛋白质聚集在特化的突触前和突触后结构处。介导蛋白质在这些位点聚集的机制仍然未知。为了研究这一过程，我们通过在培养的海马神经元中表达绿色荧光蛋白（GFP）标记的突触后致密蛋白95（PSD-95）来分析其突触靶向作用。我们发现突触后聚集依赖于PSD-95的三个元件：N端棕榈酰化、前两个PDZ结构域和一个C端靶向基序。相比之下，PDZ3、SH3或鸟苷酸激酶（GK）结构域的破坏并不影响突触靶向。棕榈酰化足以将弥散表达的SAP-97靶向到突触，并且棕榈酰化不能被其他膜结合基序所取代，这表明一种特殊的突触脂质环境介导了突触后聚集。对PSD-95的PDZ结构域和C端结构域的要求表明，蛋白质-蛋白质相互作用在突触靶向中与脂质相互作用协同发挥作用。
