Klein S, Carroll J A, Chen Y, Henry M F, Henry P A, Ortonowski I E, Pintucci G, Beavis R C, Burgess W H, Rifkin D B
Department of Cell Biology, New York University Medical School, New York, New York 10013, USA.
J Biol Chem. 2000 Feb 4;275(5):3150-7. doi: 10.1074/jbc.275.5.3150.
The post-translational methylation of the N-terminally extended or high molecular weight (HMW) forms of fibroblast growth factor-2 (FGF-2) has been shown to affect the nuclear accumulation of the growth factor. In this study, we determined the extent and position of methyl groups in HMW FGF-2. Using mass spectrometry and amino acid sequence analysis, we have shown that the 22- and 22.5-kDa forms of HMW FGF-2 contain five dimethylated arginines located at positions -22, -24, -26, -36, and -38 using the methionine residue normally used to initiate the 18-kDa form as position 0. The 24-kDa form of HMW FGF-2 contains seven to eight dimethylated arginines located at positions -48, -50, and -52, in addition to positions -22, -24, -26, -36, and -38. In vitro methylation reactions demonstrate that the N-terminal extension of HMW FGF-2 acts as a specific substrate for yeast Hmt1p and human HRMT1L2 arginine methyltransferases. These findings indicate that HMW FGF-2, with the presence of five or more dimethylated Gly-Arg-Gly repeats, contains an RGG box-like domain, which may be important for protein-protein and/or protein-RNA interactions.
成纤维细胞生长因子2（FGF-2）的N端延伸或高分子量（HMW）形式的翻译后甲基化已被证明会影响生长因子的核积累。在本研究中，我们确定了HMW FGF-2中甲基基团的程度和位置。使用质谱和氨基酸序列分析，我们发现，以通常用于起始18 kDa形式的甲硫氨酸残基为位置0，HMW FGF-2的22 kDa和22.5 kDa形式含有五个位于-22、-24、-26、-36和-38位的二甲基化精氨酸。HMW FGF-2的24 kDa形式除了含有位于-22、-24、-26、-36和-38位的二甲基化精氨酸外，还含有七个至八个位于-48、-50和-52位的二甲基化精氨酸。体外甲基化反应表明，HMW FGF-2的N端延伸是酵母Hmt1p和人HRMT1L2精氨酸甲基转移酶的特异性底物。这些发现表明，具有五个或更多二甲基化Gly-Arg-Gly重复序列的HMW FGF-2含有一个RGG盒样结构域，这可能对蛋白质-蛋白质和/或蛋白质-RNA相互作用很重要。
