Nivison H T, Sutton C A, Wilson R K, Hanson M R
Section of Genetics and Development, Cornell University, Ithaca, NY 14853-2703.
Plant J. 1994 May;5(5):613-23. doi: 10.1111/j.1365-313x.1994.00613.x.
The petunia mitochondrial fused gene (pcf), which is associated with cytoplasmic male sterility (CMS), is composed of sequences derived from atp9, coxII, and an unidentified reading frame termed urfS. Pcf transcripts are modified by editing at 11 sites. Codon usage and nearest neighbor analysis suggest that the urfS region is not derived originally from a plant mitochondrial coding region. Although the gene contains an open reading frame coding for a 43 kDa protein, a 25 kDa gene product has previously been identified (Nivison and Hanson, 1989). N-terminal sequencing revealed that the 25 kDa protein is encoded within the urfS portion of pcf and that its actual molecular mass is 19.5 kDa. Through pulse-chase labeling of protein in isolated mitochondria, the 25 kDa protein was found to be processed from a 43 kDa precursor protein representing the entire pcf gene sequence. Antibodies to synthetic peptides encoded by the atp9 and coxII portions of pcf recognized petunia ATP9 or COXII but no other mitochondrial proteins on immunoblots. Controlled proteolysis experiments showed that both the 43 kDa precursor and the 25 kDa protein are soluble or loosely associated with membranes. Thus, the 25 kDa protein appears to be the only pcf-encoded protein that accumulates in mitochondria.
矮牵牛线粒体融合基因（pcf）与细胞质雄性不育（CMS）相关，它由源自atp9、coxII的序列以及一个名为urfS的未鉴定阅读框组成。Pcf转录本在11个位点进行编辑修饰。密码子使用情况和紧邻分析表明，urfS区域并非最初源自植物线粒体编码区。尽管该基因包含一个编码43 kDa蛋白的开放阅读框，但此前已鉴定出一种25 kDa的基因产物（Nivison和Hanson，1989年）。N端测序显示，25 kDa蛋白由pcf的urfS部分编码，其实际分子量为19.5 kDa。通过对分离线粒体中的蛋白质进行脉冲追踪标记，发现25 kDa蛋白是由代表整个pcf基因序列的43 kDa前体蛋白加工而来。针对pcf的atp9和coxII部分编码的合成肽产生的抗体，在免疫印迹中能识别矮牵牛ATP9或COXII，但不能识别其他线粒体蛋白。可控蛋白酶解实验表明，43 kDa前体蛋白和25 kDa蛋白都是可溶的，或者与膜松散结合。因此，25 kDa蛋白似乎是唯一在线粒体中积累的pcf编码蛋白。
