Anti-Reverse Cap Analog (ARCA) is a modified cap analog in which the 3' OH group (closer to m7G) is replaced with –OCH3. Because of this substitution, the RNA polymerase can only initiate transcription with the remaining hydroxyl group and forcing ARCA incorporation in the forward orientation. Thus, ARCA ensures incorporation in the forward orientation only. As a result, 100% of the transcripts synthesized with ARCA at the 5' end are translatable leading to a strong stimulatory effect on translation.
References:
[1].Janowski M, et al. The legacy of mRNA engineering: A lineup of pioneers for the Nobel Prize. Mol. Ther. Nucleic Acids. 2022 Sep 13; 29: 272-284.
Anti-Reverse Cap Analog (ARCA) 是一种改良的帽类似物,其中 3' OH 基团（更接近 m7G）被 -OCH3 取代。由于这种取代,RNA 聚合酶只能用剩余的羟基启动转录,并迫使 ARCA 正向掺入。因此,ARCA 确保仅在前向结合。因此,在 5' 端用 ARCA 合成的转录本 100% 是可翻译的,从而对翻译产生强烈的刺激作用。