Almost all eukaryotic cellular mRNAs and many viral RNAs possess a modified nucleotide structure (N7-methyl guanosine, m7G) at their 5'-end, known as "Cap". This Cap plays an important role during various stages of gene expression including mRNA splicing, intracellular transport, turnover and, translation[3,4].
For synthesis of 5'-capped RNAs with in vitro transcription catalyzed by viral RNA polymerases, typically a standard Cap analog such as m7G(5')p3G is used for incorporation (Figure 1A). Since however, these simple Cap analogs are incorporated into the RNA both in the forward [m7G(5')p3G(pN)] and the reverse orientation [G(5')p3m7G(pN)] this leads to two forms of isomeric RNAs. RNAs capped with reverse 5'-Caps are poorly translated and more readily degraded.
Therefore, Anti-reverse cap analogs (ARCAs), such as m27.3'-OGp3G (Figure 1B) carrying a 3'-O-methyl group have been developed[6,7,8]. They are incorporable in the correct (i.e. forward) orientation only and were shown to yield RNA transcripts that are more efficiently translated in vitro.
Figure 1: (A) In vitro transcriptions performed in the presence of standard Cap m7GpppG are initiated by an RNA polymerase from either the guanosine or 7-methylguanosine moiety to produce correctly and reversely capped mRNA, respectively. (B) In contrast, the 3'-methyl group in ARCA prevents reverse incorporation and improves both mRNA quality and translation efficiency.
Jena Bioscience makes ARCA cap m27.3'-OGpppG available:
- from mg to g scale
- with a purity of >98 % (HPLC)
- at a price that has been significant reduced:
Also available are the standard cap analogs:
For more information please see:
 Izaurralde et al. (1994) A nuclear cap binding protein complex involved in pre-mRNA splicing. Cell 78(4):657.
 Jacobson et al. (1998) A 7-methylguanosine cap commits U3 and U8 small nuclear RNAs to the nucleolar localization pathway. Nucl. Acids. Res. 26(3):756.
 Gingras et al. (1999) eIF4 initiation factors: effectors of mRNA recruitment to ribosomes and regulators of translation. Annu. Rev. Biochem. 68:913.
 Rhoads (2009) eIF4E: New family members, new binding partners, new roles. J. Biol. Chem. 284(25):16711.
 Pasquinelli et al. (1995) Reverse 5' caps in RNAs made in vitro by phage RNA polymerases. RNA 1:957.
 Peng et al. (2002) Synthesis and application of a chain-terminating dinucleotide mRNA cap analog. Organic Letters 4:161.
 Stepinski et al. (2001) Synthesis and properties of mRNAs containing the novel "anti-reverse" cap analogues 7-methyl(3'-O-methyl)GpppG and 7-methyl(3'-deoxy)GpppG. RNA 7:1486.
 Jemielity et al. (2010) Synthetic mRNA cap analogs with a modified triphosphate bridge – synthesis, applications and prospects. New J. Chem. 34:829.
Nucleotide analogs not on stock may be available as custom synthesis, just send us an e-mail at email@example.com with any questions you may have!