Membrane-binding domain of the small G protein G25K contains an S-(all-trans-geranylgeranyl)cysteine methyl ester at its carboxyl terminus.
Membrane-binding domain of the small G protein G25K contains an S-(all-trans-geranylgeranyl)cysteine methyl ester at its carboxyl terminus.
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小 G 蛋白 G25K 的膜结合结构域在其羧基末端含有 S-（全反式香叶基香叶基）半胱氨酸甲酯。
DOI：
10.1073/pnas.88.1.286
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发表时间：
1991
影响因子：
11.1
通讯作者：
Fung,BK
中科院分区：
文献类型：
--
作者：
Yamane,HK;Farnsworth,CC;Xie,HY;Evans,T;Howald,WN;Gelb,MH;Glomset,JA;Clarke,S;Fung,BK
我们以前表明，23 kDa的鸟嘌呤核苷酸结合蛋白（G蛋白）从牛脑膜纯化的羧基甲基化，这种修饰发生在或附近的膜结合结构域。在本研究中，我们将这种小G蛋白鉴定为G25 K（以前称为Gp）。我们证明了3 H-甲基化G25 K的蛋白水解酶含有放射性标记的材料，该材料与合成的S-（香叶基香叶基）半胱氨酸甲酯在反相HPLC上共洗脱。通过过甲酸氧化的进一步处理产生与L-半胱氨酸甲酯共洗脱的放射性标记的材料，验证类异戊二烯部分和羧基甲酯位于C-末端半胱氨酸残基上。通过气相色谱-质谱联用分析从纯化的G25 K释放的材料，通过雷尼镍处理，积极确定了共价结合的脂质作为一个全反式-香叶基香叶基（C20）类异戊二烯部分。这些结果表明，geranylgeranyl修改，也许甲酯化功能在膜定位的这个小G蛋白。
We showed previously that a 23-kDa guanine nucleotide-binding protein (G protein) purified from bovine brain membranes is carboxyl methylated and that this modification occurs at or near the membrane-binding domain. In the present study, we identified this small G protein as G25K (formerly termed Gp). We demonstrated that proteolytic digests of 3H-methylated G25K contained radiolabeled material that coeluted with synthetic S-(geranylgeranyl)cysteine methyl ester on reversed-phase HPLC. Further treatment by performic acid oxidation yielded radiolabeled material that coeluted with L-cysteic acid methyl ester, verifying that the isoprenoid moiety and carboxyl methyl ester are localized on a C-terminal cysteine residue. Analysis by gas chromatography-coupled mass spectrometry of material released from purified G25K by Raney nickel treatment positively identified the covalently bound lipid as an all-trans-geranylgeranyl (C20) isoprenoid moiety. These results suggest that geranylgeranyl modification and perhaps methyl esterification function in the membrane localization of this small G protein.