Brenman J E, Christopherson K S, Craven S E, McGee A W, Bredt D S
Department of Physiology, University of California at San Francisco School of Medicine, 94143-0444, USA.
J Neurosci. 1996 Dec 1;16(23):7407-15. doi: 10.1523/JNEUROSCI.16-23-07407.1996.
Nitric oxide (NO) formation in brain is regulated by the calcium/calmodulin dependence of neuronal NO synthase (nNOS). Calcium influx through NMDA-type glutamate receptors is efficiently coupled to nNOS activity, whereas many other intracellular calcium pathways are poorly coupled. To elucidate possible mechanisms responsible for this coupling, we performed yeast two-hybrid screening to identify proteins that interact with nNOS. Two nNOS interacting proteins were identified: the postsynaptic density proteins PSD-93 and PSD-95. Here, we report the cloning and characterization of PSD-93. PSD-93 is expressed in discrete neuronal populations as well as in specific non-neuronal cells, and it exhibits complex molecular diversity attributable to tissue-specific alternative splicing. PSD-93, like PSD-95, binds to nNOS and to the NMDA receptor 2B. PSD-93, however, is unique among PSD-95/SAP-90 family members in its expression in Purkinje neuron cell bodies and dendrites. We also demonstrate that the PDZ domain at the N terminus of nNOS is required, but it is not sufficient for interaction with PSD-93/95. Given that PSD-93 and PSD-95 each contain multiple potential binding sites for nNOS and the NMDA receptor, complexes involving oligomers of PSD-93/95 may help account for the functional as well as the physical coupling of nNOS to NMDA receptors.
大脑中一氧化氮（NO）的生成受神经元型一氧化氮合酶（nNOS）的钙/钙调蛋白依赖性调控。通过NMDA型谷氨酸受体的钙内流与nNOS活性有效偶联，而许多其他细胞内钙途径的偶联效率较低。为了阐明这种偶联的可能机制，我们进行了酵母双杂交筛选以鉴定与nNOS相互作用的蛋白质。鉴定出两种与nNOS相互作用的蛋白质：突触后致密蛋白PSD-93和PSD-95。在此，我们报告PSD-93的克隆和特性。PSD-93在离散的神经元群体以及特定的非神经元细胞中表达，并且由于组织特异性可变剪接而表现出复杂的分子多样性。与PSD-95一样，PSD-93与nNOS和NMDA受体2B结合。然而，PSD-93在浦肯野神经元细胞体和树突中的表达在PSD-95/SAP-90家族成员中是独特的。我们还证明nNOS N端的PDZ结构域是必需的，但不足以与PSD-93/95相互作用。鉴于PSD-93和PSD-95各自包含多个nNOS和NMDA受体的潜在结合位点，涉及PSD-93/95寡聚体的复合物可能有助于解释nNOS与NMDA受体的功能以及物理偶联。
