The presence of a Leu-Gly-Asn repeat-enriched protein (LGN), a putative binding partner of transducin, in ROD photoreceptors.
The presence of a Leu-Gly-Asn repeat-enriched protein (LGN), a putative binding partner of transducin, in ROD photoreceptors.
复制标题
ROD 光感受器中存在亮氨酸-甘氨酸-天冬氨酸重复序列富集蛋白 (LGN)，它是转导蛋白的假定结合伴侣。
DOI：
10.1167/iovs.04-1006
复制
发表时间：
2005
影响因子：
4.4
通讯作者：
Slepak,VladlenZ
中科院分区：
文献类型：
--
作者：
Nair,KSaidas;Mendez,Ana;Blumer,JoeB;Rosenzweig,DerekH;Slepak,VladlenZ
目的.异源三聚体G蛋白由作为鸟嘌呤核苷酸交换因子（GEF）的受体和作为鸟苷三磷酸酶（GT3）激活蛋白（GAP）的RGS蛋白调节。鸟苷二磷酸（GDP）解离抑制剂（GDI），如G蛋白信号传导（AGS）-1和-3的活化剂和Leu-Gly-Asn重复富集（LGN）蛋白调节G蛋白的Gi家族。AGS 3和LGN含有四个特征性G蛋白调节器（GPR）结构域，负责其GDI功能。本研究调查的存在下的GDI在感光细胞中transducin。使用AGS和LGN蛋白的特异性抗体对牛和小鼠视网膜进行蛋白质印迹分析。用免疫荧光显微镜观察小鼠视网膜切片，用蔗糖密度梯度分离视网膜裂解液，研究LGN在视网膜中的亚细胞定位。使用GST融合LGN构建物的下拉测定、免疫共沉淀和GTPγS结合测定研究LGN与转导素的相互作用。LGN在视网膜中表达，但不表达AGS 3和AGS 1，在光和暗条件下，LGN主要定位于感光细胞的内节和外丛状层。LGN存在于细胞溶质、细胞膜和耐洗涤剂的细胞骨架部分中。LGN相对于转导素的量为至少1：15。转导素的α亚基在GDP结合状态下与内源性和重组LGN相互作用，LGN的重组GPR结构域降低了GTP交换的速率。光感受器内节含有LGN，LGN可与transducin的α亚基结合并潜在地调节其功能。
purpose. Heterotrimeric G proteins are regulated by receptors that act as guanine nucleotide exchange factors (GEFs) and by RGS proteins, which act as guanosine triphosphatase (GTPase) activating proteins (GAPs). Guanosine diphosphate (GDP) dissociation inhibitors (GDIs), such as activators of G protein signaling (AGS)-1 and-3 and Leu-Gly-Asn repeat–enriched (LGN) proteins regulate the Gi family of G proteins. AGS3 and LGN contain four characteristic G protein regulator (GPR) domains that are responsible for its GDI function. This study investigates the presence of a GDI for transducin in photoreceptor cells.methods. Western blot analysis of bovine and mouse retina was performed using specific antibodies to AGS and LGN proteins. The subcellular localization of LGN in retina was studied by immunofluorescence microscopy of mouse retinal sections and fractionation of retinal lysates, using sucrose density gradients. The interaction of LGN with transducin was studied using pull-down assays with GST-fused LGN constructs, co-immunoprecipitation and assays for GTPγS binding.results. LGN, but not AGS3 and AGS1, was present in the retina, where it was localized mostly in the inner segments and outer plexiform layer of photoreceptor cells in both light and dark conditions. LGN was present in the cytosol, membrane, and the detergent-resistant cytoskeletal fraction. The amount of LGN relative to transducin was at least 1: 15. The α subunit of transducin in its GDP-bound state interacted with endogenous and recombinant LGN, and the recombinant GPR domain of LGN reduced the rate of GTP exchange.conclusions. Photoreceptor inner segments contain LGN, which can bind to the α subunit of transducin and potentially regulate its function.