Phorbol esters modulate the Ras exchange factor RasGRP3.
Phorbol esters modulate the Ras exchange factor RasGRP3.
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发表时间：
2001-02
期刊：
影响因子：
11.2
通讯作者：
P. Lorenzo;Justin W. Kung;D. Bottorff;S. Garfield;James C. Stone;P. M. Blumberg
中科院分区：
文献类型：
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作者：
P. Lorenzo;Justin W. Kung;D. Bottorff;S. Garfield;James C. Stone;P. M. Blumberg
RasGRP代表了一类新的鸟嘌呤核苷酸交换因子的原型，其激活小GTP酶。鸟苷酸释放蛋白（GRP）家族成员包含与酿酒酵母的Ras交换因子CDC 25相关的催化结构域。它们还含有类似于一对钙结合EF-手的基序和类似于蛋白激酶C的二酰基甘油相互作用结构域的C1结构域。在人脑cDNA文库中鉴定的KIAA 0846序列编码GRP家族的一个成员，我们称之为RasGRP 3。我们在这里表明，RasGRP 3结合佛波酯具有高亲和力。这种结合依赖于阴离子磷脂，这是佛波酯结合C1结构域蛋白的特征。此外，佛波醇酯也引起了完整细胞中RasGRP 3交换活性的激活，如通过RasGTP的增加和细胞外调节激酶的磷酸化所确定的。最后，佛波醇1,2-肉豆蔻酸酯13-乙酸酯和二酰基甘油类似物1，2-二辛酰基-sn-甘油诱导RasGRP 3重新分布到HEK-293细胞中的质膜和/或核周区域，如使用绿色荧光融合蛋白所证明的。我们的结论是，RasGRP 3作为一个PKC-独立的途径，连接肿瘤促进佛波酯与Ras GTPases的激活。
RasGRP represents the prototype of a new class of guanine nucleotide exchange factors that activate small GTPases. The guanyl nucleotide-releasing protein (GRP) family members contain catalytic domains related to CDC25, the Ras exchange factor of Saccharomyces cerevisiae. They also contain a motif resembling a pair of calcium-binding EF-hands and a C1 domain similar to the diacylglycerol interaction domain of protein kinase C. The sequence of KIAA0846, identified in a human brain cDNA library, encodes a member of the GRP family that we refer to as RasGRP3. We show here that RasGRP3 bound phorbol esters with high affinity. This binding depended on anionic phospholipids, which is characteristic of phorbol ester binding to C1 domain proteins. In addition, phorbol esters also caused activation of the RasGRP3 exchange activity in intact cells, as determined by an increase in RasGTP and phosphorylation of the extracellular-regulated kinases. Finally, both phorbol 12-myristate 13-acetate and the diacylglycerol analogue 1,2-dioctanoyl-sn-glycerol induced redistribution of RasGRP3 to the plasma membrane and/or perinuclear area in HEK-293 cells, as demonstrated using a green fluorescent fusion protein. We conclude that RasGRP3 serves as a PKC-independent pathway to link the tumor-promoting phorbol esters with activation of Ras GTPases.