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Background ARCAs Cap Services Highlights FAQs Published Data


As the DNA template does not encode the 5' end cap, a synthetic cap analogue must be added to the mRNA. Cap analogs, which affect mRNA translation and transformation, are valuable tools for studying gene expression, and are often associated with therapy. Anti-reverse cap analog (ARCA) is a cap analog that produces immunogenic cap 0 for the production of capped transcripts during in vitro transcription.

  • Introduction of ARCAs Cap

As a platform technology, synthetic mRNA is increasingly used to express proteins needed in cell culture and even in vivo. The 5' cap of mRNA is an important feature that affects the stability and translation efficiency of mRNA, and ultimately affects the total protein content of mRNA expression. The capping of in vitro transcriptional mRNA is usually achieved by adding the corresponding dinucleotide cap analog to the reaction.

In the presence of cap dinucleotide, when the mRNA was blocked by transcription in vitro, it was found that m7GpppG cap analog could bind in two orientations, and only the correctly located derivatives, namely, m7G, were in the outer position and participated in the translation process. This has been solved by designing a modified cap analogue with O-CH3 replacing the 3'- or 2'- hydroxyl group of m7G, so it is called "ARCA".

Structural requirements for generating ARCA cap analog.

Fig.1 Structural requirements for a cap analog to be incorporated into mRNA and to produce ARCAs.1

  • Features of ARCAs Cap
    ARCA contains hydrogen (O-H substitution), fluorine (o-f substitution), sulfur (O-S substitution) or larger substituents. ARCA can only be inserted in the right direction to form mRNA. This kind of mRNAs has high translation efficiency in vitro and in cultured cells.
    Generally speaking, the modification of ARCAs cap has the following purposes:
    • Disruption or even complete destruction of biological activity (e.g., inhibition of degradation by decapping enzymes).
    • Increased affinity for specific cap-binding proteins, thereby enhancing related biological activity.
    • New properties of cap like structures without interfering with mRNA biological activity.
  • Application of ARCAs Cap

As a therapeutic drug for gene therapy, mRNA has huge application potential. It has been applied in some ongoing clinical trials, which is the driving force for the development of new mRNA cap modification molecular tools and the construction of new cap-based molecular probes. Synthetic cap analogs are useful research tools that can facilitate the study of cap-related processes at the molecular level and in biochemical and biological experiments, and may even eventually lead to the development of new therapeutic methods.

Due to the excellent inhibitory properties of ARCA, such compounds can help to prepare mRNA transcripts with high translation activity. To date, ARCAs cap RNA synthesized by in vitro transcription has been widely used in the study of mRNA function and metabolism, in vitro protein synthesis and expression of exogenous mRNA in living cells.

ARCAs Cap Services

Creative Biolabs provides products and services with promising quality and exceptional price. Our mRNA service allows researchers to customize synthesis and introduce modifications to produce transcripts that are best suited for downstream applications. Based on years of intensive research, we provide customized high-quality ARCAs cap mRNA synthesis services. mRNA can be generated by DNA template provided by customers, or we can provide all-round services from scratch. Please contact us for more information.

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  • High Translation Efficiency: ARCAs cap ensures high translation efficiency in vitro and in cultured cells.
  • Stability and Protection: The cap structure protects mRNA from degradation by decapping enzymes.
  • Custom Modifications: Offers various modifications like O-H, O-F, and O-S substitutions to enhance biological activity.
  • Enhanced Cap-Binding: Increased affinity for specific cap-binding proteins to boost related biological activities.
  • High-Quality Synthesis: Ensures top-notch, customized ARCAs cap mRNA synthesis services.


Q: What advantages do ARCAs caps have over traditional mRNA caps?

A: ARCAs caps ensure correct incorporation orientation, leading to higher translation efficiency and stability compared to traditional caps.

Q: How does Creative Biolabs verify the quality of ARCAs capped mRNA?

A: We use rigorous quality control measures, including analytical techniques to confirm cap structure and mRNA integrity.

Q: Does Creative Biolabs offer consultation services for ARCAs cap projects?

A: Yes, we provide comprehensive consultation to tailor the ARCAs capping process to specific research needs.

Q: What modifications can be made to ARCAs caps?

A: Modifications include O-H, O-F, and O-S substitutions, which can alter biological activity and enhance protein binding.

Q: How does the ARCAs cap affect mRNA translation?

A: By ensuring correct orientation, ARCAs caps significantly improve translation efficiency in vitro and in cultured cells.

Published Data

The article investigates the use of anti-reverse cap analogs (ARCA) in enhancing the efficiency of mRNA transfection into mesenchymal stem cells (MSCs). The study explores the effects of different mRNA capping methods, including ARCA and its beta-thiophosphate derivatives (b-S-ARCA D1 and b-S-ARCA D2). It finds that b-S-ARCA D1 leads to higher protein production but with lower MSC metabolic activity, while ARCA ensures correct cap orientation, improving mRNA stability and translation efficiency. This research highlights the potential of ARCA-capped mRNA for clinical applications in cell-based therapies.

Impact of ARCA- or β-S-ARCA D1-capped mRNA on the metabolic activity of MSCs.

Fig.2 Metabolic activity of MSCs transfected with mRNA capped with different 5' cap analogs.2

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  1. Warminski, M.; et al. Applications of Phosphate Modification and Labeling to Study (m)RNA Caps. Topics in Current Chemistry. 2017, 375(1): 16-16.
  2. Andrzejewska, Anna, et al. "Mesenchymal stem cell engineering by ARCA analog-capped mRNA." Molecular Therapy-Nucleic Acids 33 (2023): 454-468.
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