GTP gamma S inhibits organelle transport along axonal microtubules.
GTP gamma S inhibits organelle transport along axonal microtubules.
复制标题
DOI：
10.1083/jcb.120.2.467
复制
发表时间：
1993-01
期刊：
影响因子：
--
通讯作者：
Brady ST
中科院分区：
文献类型：
--
作者：
Bloom GS;Richards BW;Leopold PL;Ritchey DM;Brady ST
有膜的细胞器通过细胞质的运动经常发生沿着微管，在神经元特异性的快速轴突运输的情况下。为了阐明如何微管为基础的细胞器运动的调节，药理学探针的GTP结合蛋白，或蛋白激酶或磷酸酶灌注到轴浆挤压鱿鱼（Loligo pealei）巨大的轴突，和快速轴突运输的影响进行了监测定量视频增强光学显微镜。GTP gamma S导致细胞器运输速度呈浓度依赖性和时间依赖性下降。GDP β S是一种效力较低的抑制剂。过量的GTP，而不是GDP，掩盖了共灌注的GTP γ S的作用。GTP γ S对转运的影响不被蛋白激酶（K-252 a）或磷酸酶（微囊藻毒素LR和冈田酸）的广谱抑制剂或如前所述的ATP γ S所模拟。因此，GTP γ S对细胞器运动的抑制是鸟嘌呤核苷酸特异性的，显然不涉及硫代磷酸基团向蛋白质的不可逆转移。相反，这些数据意味着轴突中的细胞器运输是由一个或多个GTP结合蛋白的GTP水解和核苷酸交换的循环来调节的。快速轴突运输不受AlF 4-干扰，表明GTP γ S敏感因子不包括异源三聚体G蛋白。GTP γ S的潜在轴浆靶点包括发动蛋白和多种小GTP结合蛋白，它们被证明存在于鱿鱼轴浆中。这些集体研究结果表明，一种新的策略，用于调节基于微管的细胞器运输和GTP结合蛋白的新作用。
Movements of membrane-bounded organelles through cytoplasm frequently occur along microtubules, as in the neuron-specific case of fast axonal transport. To shed light on how microtubule-based organelle motility is regulated, pharmacological probes for GTP-binding proteins, or protein kinases or phosphatases were perfused into axoplasm extruded from squid (Loligo pealei) giant axons, and effects on fast axonal transport were monitored by quantitative video-enhanced light microscopy. GTP gamma S caused concentration-dependent and time-dependent declines in organelle transport velocities. GDP beta S was a less potent inhibitor. Excess GTP, but not GDP, masked the effects of coperfused GTP gamma S. The effects of GTP gamma S on transport were not mimicked by broad spectrum inhibitors of protein kinases (K-252a) or phosphatases (microcystin LR and okadaic acid), or as shown earlier, by ATP gamma S. Therefore, suppression of organelle motility by GTP gamma S was guanine nucleotide- specific and evidently did not involve irreversible transfer of thiophosphate groups to protein. Instead, the data imply that organelle transport in the axon is modulated by cycles of GTP hydrolysis and nucleotide exchange by one or more GTP-binding proteins. Fast axonal transport was not perturbed by AlF4-, indicating that the GTP gamma S- sensitive factors do not include heterotrimeric G-proteins. Potential axoplasmic targets of GTP gamma S include dynamin and multiple small GTP-binding proteins, which were shown to be present in squid axoplasm. These collective findings suggest a novel strategy for regulating microtubule-based organelle transport and a new role for GTP-binding proteins.