Modulation and Targeting of Kainate Receptors

描述： 谷氨酸可控制 NMDA、AMPA 和红藻氨酸离子型受体。对于红藻氨酸 受体，但对其功能如何调节知之甚少 通过亚基组成或锚定分子，例如突触后密度 蛋白质（PSD/SAP）。我们最近的工作表明 PSD-95/SAP9O 共定位 与突触处的红藻氨酸受体结合，结合红藻氨酸受体 KA2 和 GluR6 亚基，并显着改变 GluR6 和 KA2/G1uR6 生理学（Garcia 等 等，1998）。我们发现酪氨酸磷酸化与 改变生理反应和潜在的调节分子， src 和 mss4（鸟嘌呤核苷酸交换因子）优先关联 分别为 KA2 和 PSD-95/SAP9O。此外，我们还发现，两者 关联受 KA2-PSD-95/SAP9O 相互作用调节，并且 此外，SAP97 无法结合含有 KA2 的受体。在一起， 结果表明 PSD 蛋白可能不仅具有锚定功能 突触位点的受体，而且还调节受体活性，其中 受体亚型存在于给定位点。 该提案将建立 PSD-95/SAP9O 调节红藻氨酸的机制 受体功能和靶向。我们将评估它如何调节受体 活性以及调节是否取决于受体亚基组成，确定 激动剂亲和力、脱敏特性和对抑制剂的敏感性。 对于潜在的机制，我们将研究配体（例如 GKAP）的结合如何， GK 结构域可能会促进 PSD-95 的 SH3 结构域与 KA2，KA2 和 PSD-95 上决定酪氨酸的分子位点 磷酸化，以及 mss4 和 PSD-95/SAP9O 上调节的位点 mss4-PSD-95/SAP9O-KA2 相互作用将被识别。生理学 这些相互作用以及 src 对 KA2 和 PSD-95 的影响将是 通过表达活性和非活性酶与受体亚基而建立 （野生型与突变型）。确定 mss4 对受体的潜在调节 靶向、受体表面表达和受体分布 （集群与非集群）将被评估。这些研究预计将 提供有关如何确定功能特性的新颖信息 通过控制受体聚集/靶向的机制 特定的亚基组成。

DESCRIPTION: Glutamate gates NMDA, AMPA and kainate ionotropic receptors. For kainate receptors, comparatively little is known about how their function is regulated by subunit composition or anchoring molecules such as postsynaptic density proteins (PSD/SAP). Our recent work demonstrates that PSD-95/SAP9O colocalizes with kainate receptors at synapses, binds the kainate receptor KA2 and GIuR6 subunits, and significantly modifies GluR6 and KA2/G1uR6 physiology (Garcia et al., 1998). We find that tyrosine phoshorylation correlates with the modification of physiological response and that potential regulatory molecules, src and mss4 (a guanine nucleotide exchange factor) preferentially associate with, respectively, KA2 and PSD-95/SAP9O. Furthermore, we also find that both associations are regulated by the KA2-PSD-95/SAP9O interaction, and additionally that SAP97 is unable to bind KA2-containing receptors. Together, the results imply that PSD proteins may function not only in anchoring receptors at synaptic Sites, but also in regulating receptor activity and which receptor subtypes are present in a given site. This proposal will establish mechanisms by which PSD-95/SAP9O regulates kainate receptor function and targeting. We will assess how it regulates receptor activity and if regulation depends on receptor subunit composition, determining agonist affinities, desensitization properties and sensitivity to inhibitors. For potential mechanisms, we will examine how binding of ligands, such as GKAP, to the GK domain may promote the association of the SH3 domain of PSD-95 with KA2, the molecular sites on KA2 and PSD-95 that determine tyrosine phosphorylation, as well as the sites on mss4 and PSD-95/SAP9O that regulate mss4-PSD-95/SAP9O-KA2 interactions will be identified. The physiological effects of these interactions and those of src on KA2 and PSD-95, will be established by expressing active and inactive enzymes with receptor subunits (wild-type vs. mutated). To determine potential mss4 regulation of receptor targeting, the surface expression of receptors and receptor distribution (clustered vs. unclustered) will be evaluated. These studies are expected to provide novel information on how functional properties can be determined through mechanisms controlling the clustering/targeting of receptors of specific subunit composition.