Ambion™ Anti-Reverse Cap Analog (ARCA) is a cap analog used during in vitro transcription for the generation of capped transcripts. ARCA is modified in a way that ensures incorporation in the forward orientation only. Anti-Reverse Cap Analog (ARCA) is a modified cap analog in which the 3' OH group (closer to m⁷G) is replaced with –OCH₃ (see schematic). Because of this substitution, the RNA polymerase can only initiate transcription with the remaining hydroxyl group thus forcing ARCA incorporation in the forward orientation. As a result, unlike transcripts synthesized with conventional cap analog, 100% of the transcripts synthesized with ARCA at the 5' end are translatable leading to a strong stimulatory effect on translation.

Quality Control:
Each Cap Analog is rigorously tested for contaminating nonspecific endonuclease, exonuclease, and RNase activity. Each is also assayed for the efficient synthesis of capped in vitro transcripts by using the cap analog in functional MEGAscript™ In Vitro transcription and Retic Lysate translation reactions.

Accessory Products:
Complete kits are available with all the necessary reagents for the in vitro transcription of capped RNA transcripts. The mMESSAGE mMACHINE™ T7 Ultra Kit includes ARCA (SKU #AM1345). Also available are kits containing conventional cap analog; mMESSAGE mMACHINE™ T7 (SKU #AM1344), T3 (SKU #AM1348), and SP6 (SKU #AM1340) Kits. The Retic Lysate IVT™ (SKU #AM1200) for in vitro translation of mRNA is also available.