In its active form, the GTP-binding protein rab8 interacts with a stress-activated protein kinase.
In its active form, the GTP-binding protein rab8 interacts with a stress-activated protein kinase.
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在其活性形式下，GTP 结合蛋白 rab8 与应激激活蛋白激酶相互作用。
DOI：
10.1073/pnas.93.10.5151
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发表时间：
1996
影响因子：
11.1
通讯作者：
Sabatini,DD
中科院分区：
文献类型：
--
作者：
Ren,M;Zeng,J;DeLemos-Chiarandini,C;Rosenfeld,M;Adesnik,M;Sabatini,DD
Rab 8是一种小的GTP结合蛋白，其在极化上皮细胞（MDCK）中从高尔基体网络到基底外侧质膜的囊泡转运中以及在海马神经元中到树突表面的囊泡转运中起作用。与大多数其他rab蛋白一样，rab 8发挥其功能的精确分子相互作用仍有待阐明。在这里，我们报告的识别和完整的cDNA衍生的氨基酸序列的鼠rab 8相互作用蛋白（rab 8ip），特别是相互作用与rab 8在GTP依赖的方式。Rab 8ip与GC激酶具有93%的同一性，GC激酶是一种最近在人类淋巴组织中发现的丝氨酸/苏氨酸蛋白激酶，在应激反应中被激活。与GC激酶一样，rab 8ip具有蛋白激酶活性，其表现为经典丝氨酸/苏氨酸蛋白激酶底物、髓鞘碱性蛋白和酪蛋白的自磷酸化和磷酸化。当在转染的293 T细胞中共表达时，rab 8和rab 8ip/GC激酶形成复合物，该复合物可以通过与针对rab 8的抗体的免疫沉淀来回收。细胞分级分离和免疫荧光分析表明，在MDCK细胞中，内源性rab 8ip存在于胞质溶胶中，并作为外周膜蛋白集中在高尔基体区域和基底外侧质膜结构域，网站rab 8本身也位于。鉴于最近的证据表明，rab蛋白可能通过促进SNARE复合物的稳定化而起作用，rab 8与rab 8ip/GC激酶的特异性GTP依赖性缔合提高了rab调节的蛋白磷酸化对于囊泡靶向或融合是重要的可能性。此外，rab 8ip/GC激酶可用于调节响应于应激刺激的分泌。
Rab8 is a small GTP-binding protein that plays a role in vesicular transport from the trans-Golgi network to the basolateral plasma membrane in polarized epithelial cells (MDCK), and to the dendritic surface in hippocampal neurons. As is the case for most other rab proteins, the precise molecular interactions by which rab8 carries out its function remain to be elucidated. Here we report the identification and the complete cDNA-derived amino acid sequence of a murine rab8-interacting protein (rab8ip) that specifically interacts with rab8 in a GTP-dependent manner. Rab8ip displays 93% identity with the GC kinase, a serine/threonine protein kinase recently identified in human lymphoid tissue that is activated in the stress response. Like the GC kinase, rab8ip has protein kinase activity manifested by autophosphorylation and phosphorylation of the classical serine/threonine protein kinase substrates, myelin basic protein and casein. When coexpressed in transfected 293T cells, rab8 and the rab8ip/GC kinase formed a complex that could be recovered by immunoprecipitation with antibodies to rab8. Cell fractionation and immunofluorescence analyses indicate that in MDCK cells endogenous rab8ip is present both in the cytosol and as a peripheral membrane protein concentrated in the Golgi region and basolateral plasma membrane domains, sites where rab8 itself is also located. In light of recent evidence that rab proteins may act by promoting the stabilization of SNARE complexes, the specific GTP-dependent association of rab8 with the rab8ip/GC kinase raises the possibility that rab-regulated protein phosphorylation is important for vesicle targeting or fusion. Moreover, the rab8ip/GC kinase may serve to modulate secretion in response to stress stimuli.