Goodman L E, Judd S R, Farnsworth C C, Powers S, Gelb M H, Glomset J A, Tamanoi F
Department of Biochemistry and Molecular Biology, University of Chicago, IL 60637.
Proc Natl Acad Sci U S A. 1990 Dec;87(24):9665-9. doi: 10.1073/pnas.87.24.9665.
Ras proteins are post-translationally modified by farnesylation. In the present investigation, we identified an activity in crude soluble extracts of yeast cells that catalyzes the transfer of a farnesyl moiety from farnesyl pyrophosphate to yeast RAS2 protein. RAS2 proteins having a C-terminal Cys-Ali-Ali-Xaa sequence (where Ali is an aliphatic amino acid and Xaa is the unspecified C-terminal amino acid) served as substrates for this reaction, whereas RAS2 proteins with an altered or deleted Cys-Ali-Ali-Xaa sequence did not. A yeast mutant, dpr1/ram1, originally isolated as a Ras-processing mutant was shown to be defective in farnesyltransferase activity. In addition, another mutant, ram2, also was defective in the transferase activity. These results demonstrate that at least two genes, DPR1/RAM1 and RAM2, are required for the farnesyltransferase activity in yeast.
Ras蛋白在翻译后会被法尼基化修饰。在本研究中，我们在酵母细胞的粗可溶性提取物中鉴定出一种活性，它能催化法尼基焦磷酸中的法尼基部分转移至酵母RAS2蛋白上。具有C端Cys-Ali-Ali-Xaa序列（其中Ali为脂肪族氨基酸，Xaa为未指定的C端氨基酸）的RAS2蛋白可作为该反应的底物，而Cys-Ali-Ali-Xaa序列发生改变或缺失的RAS2蛋白则不能作为底物。最初作为Ras加工突变体分离得到的酵母突变体dpr1/ram1，被证明在法尼基转移酶活性方面存在缺陷。此外，另一个突变体ram2在转移酶活性方面也存在缺陷。这些结果表明，酵母中的法尼基转移酶活性至少需要两个基因，即DPR1/RAM1和RAM2。
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