Myristoylation-facilitated binding of the G protein ARF1(GDP) to membrane phospholipids is required for its activation by a soluble nucleotide exchange factor
Myristoylation-facilitated binding of the G protein ARF1(GDP) to membrane phospholipids is required for its activation by a soluble nucleotide exchange factor
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DOI：
10.1074/jbc.271.3.1573
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发表时间：
1996-01-19
影响因子：
4.8
通讯作者：
Paris, S
中科院分区：
文献类型：
--
作者：
Franco, M;Chardin, P;Paris, S
我们研究了n -肉豆蔻酰化在牛adp -核糖基化因子1 （ARF1）激活中的作用。我们之前的研究表明，肉豆肉化可以在磷脂囊泡存在的情况下，在生理Mg2+水平下，在ARF1上发生一些自发的gdp - gtp交换（France， M., Chardin， P., Chabre， M., and Paris， S, (1995) J, Biol, Chem, 270, 1337-1341）。在这里，我们报告说，通过添加从牛视网膜中获得的可溶性部分，这种基础核苷酸交换可以加速（最多5倍）。这种加速被brefeldin A （IC50 = 2 μ M）和胰蛋白酶处理视网膜提取物完全消除，正如预期的arf特异性鸟嘌呤核苷酸交换因子，为了加速ARF1的GDP释放，这种可溶性交换因子绝对需要ARF1的肉豆醇化和磷脂囊泡的存在，视网膜提取物还刺激5'-3-0-（硫）-三磷酸(GTP？这些观察结果，加上我们之前的发现，肉豆酰化和非肉豆酰化形式的ARF(GTP γ s)，但只有肉豆酰化形式的ARF（GDP）与膜磷脂结合，表明：(i)视网膜交换因子仅作用于膜结合的ARF；（ii）肉豆蔻酸酯不参与ARF1与交换因子之间的蛋白-蛋白相互作用；（iii） n-肉豆蔻酸酯化仅仅通过促进ARF（GDP）与膜磷脂的结合，就促进了ARF1上自发的和催化的GDP- gtp交换。
We have investigated the role of N-myristoylation in the activation of bovine ADP-ribosylation factor 1 (ARF1). We previously showed that myristoylation allows some spontaneous GDP-to-GTP exchange to occur on ARF1 at physiological Mg2+ levels in the presence of phospholipid vesicles (France, M., Chardin, P., Chabre, M., and Paris, S, (1995) J, Biol, Chem, 270, 1337-1341), Here, we report that this basal nucleotide exchange can be accelerated (by up to 5-fold) by addition of a soluble fraction obtained from bovine retinas, This acceleration is totally abolished by brefeldin A (IC50 = 2 mu M) and by trypsin treatment of the retinal extract, as expected for an ARF-specific guanine nucleotide exchange factor, To accelerate GDP release from ARF1, this soluble exchange factor absolutely requires myristoylation of ARF1 and the presence of phospholipid vesicles, The retinal extract also stimulates guanosine 5'-3-0-(thio)-triphosphate (GTP?IS) release from ARF1 in the presence of phospholipids, but in this case myristoylation of ARF is not required, These observations, together with our previous findings that both myristoylated and nonmyristoylated forms of ARF(GTP gamma s) but only the myristoylated form of ARF(GDP) bind to membrane phospholipids, suggest that (i) the retinal exchange factor acts only on membrane-bound ARF, (ii) the myristate is not involved in the protein-protein interaction between ARF1 and the exchange factor, and (iii) N-myristoylation facilitates both spontaneous and catalyzed GDP-to-GTP exchange on ARF1 simply by facilitating the binding of ARF(GDP) to membrane phospholipids.