Chen W J, Andres D A, Goldstein J L, Brown M S
Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235.
Proc Natl Acad Sci U S A. 1991 Dec 15;88(24):11368-72. doi: 10.1073/pnas.88.24.11368.
The complete amino acid sequence of the alpha subunit of heterodimeric p21ras protein farnesyltransferase from rat has been deduced from the sequence of a cloned cDNA. The cDNA encodes a 377-amino acid protein that migrates on NaDodSO4/polyacrylamide gels identically to the alpha subunit purified from rat brain. When introduced into mammalian cells by transfection, the cDNA for the alpha subunit produced no immunodetectable protein or farnesyltransferase activity unless the cells were simultaneously transfected with a cDNA encoding beta subunit. In light of previous evidence that alpha subunit forms a heterodimer with at least two different beta subunits, current data suggest a mechanism for coordinating amounts of alpha and beta subunits. If an alpha subunit were stable only as a complex with a beta subunit, the number of alpha subunits would be automatically maintained at a level just sufficient to balance all beta subunits, thereby avoiding the potentially toxic overaccumulation of free alpha subunits.
已从克隆的cDNA序列推导得出大鼠异二聚体p21ras蛋白法尼基转移酶α亚基的完整氨基酸序列。该cDNA编码一种377个氨基酸的蛋白质，它在NaDodSO4/聚丙烯酰胺凝胶上的迁移情况与从大鼠脑中纯化得到的α亚基相同。当通过转染将α亚基的cDNA导入哺乳动物细胞时，除非细胞同时被编码β亚基的cDNA转染，否则该cDNA不会产生可免疫检测到的蛋白质或法尼基转移酶活性。鉴于先前的证据表明α亚基与至少两种不同的β亚基形成异二聚体，目前的数据提示了一种协调α亚基和β亚基数量的机制。如果α亚基仅作为与β亚基的复合物才稳定，那么α亚基的数量将自动维持在刚好足以平衡所有β亚基的水平，从而避免游离α亚基潜在的毒性过度积累。
