Perron Karl, Goldschmidt-Clermont Michel, Rochaix Jean-David
Department of Molecular Biology, University of Geneva, 1211 Geneva, Switzerland.
RNA. 2004 Apr;10(4):704-11. doi: 10.1261/rna.5237804.
The psaA gene of the green alga Chlamydomonas reinhardtii consists of three exons that are widely separated on the chloroplast genome and transcribed independently. The exons are flanked by group II intron sequences. Maturation of the psaA mRNA requires two steps of splicing in trans between the transcripts of exons 1, 2, and 3. At least 14 nuclear loci and one chloroplast gene (tscA) are involved in this process. Recently the genes of three of these nuclear factors have been cloned. Raa3 is involved in the first trans-splicing reaction, and Raa1 and Raa2 are required for the second trans-splicing reaction. Here we show that Raa1 and Raa2 can be coimmunoprecipitated and that they are part of a high molecular weight complex of 400-500 kD. The size and integrity of the complex are affected by mutations in other complementation groups, suggesting that the corresponding proteins may also be components of this multiprotein complex or required for its assembly. Raa1 is also associated with a larger complex.
莱茵衣藻的psaA基因由三个外显子组成，这些外显子在叶绿体基因组上广泛分离且独立转录。外显子两侧是II类内含子序列。psaA mRNA的成熟需要外显子1、2和3的转录本之间进行两步反式剪接。至少14个核基因座和一个叶绿体基因（tscA）参与此过程。最近，其中三个核因子的基因已被克隆。Raa3参与第一次反式剪接反应，而Raa1和Raa2是第二次反式剪接反应所必需的。在这里，我们表明Raa1和Raa2可以被共免疫沉淀，并且它们是一个400 - 500 kD的高分子量复合物的一部分。该复合物的大小和完整性受到其他互补组中突变的影响，这表明相应的蛋白质可能也是这个多蛋白复合物的组成部分或其组装所必需的。Raa1还与一个更大的复合物相关联。
