m7G[5']ppp[5']G & G[5']ppp[5']G
A modified nucleotide structure called a 'cap' is present on the 5'-end of most naturally-occurring eukaryotic mRNAs and many viral RNAs. Substitution of Cap Analogue for a portion of the GTP present in an in vitro transcription reaction results in the synthesis of transcripts with a cap on the 5'-end of the RNA.
The cap structure is involved in the initiation of protein synthesis and in mRNA processing and stability in vivo. Many viral RNAs are infectious only when capped, and uncapped RNAs introduced into cells via transfection or microinjection are rapidly degraded by cellular RNases. Therefore, RNA prepared for microinjection into oocytes or for transfection into eukaryotic cells should be capped. In vitro, capped RNAs are translated more efficiently than uncapped transcripts in rabbit reticulocyte lysate or wheat germ translation systems. Transcripts synthesised for use in in vitro RNA splicing experiments may also need to be capped. Capping does reduce RNA yields relative to transcription reactions without Cap Analogue, since the GTP concentration is reduced in the reaction to favour incorporation of the cap. However, with the appropriate conditions and high-quality reagents such as the AmpliScribe™ High Yield Transcription Kits, a large proportion of the transcripts synthesised will be capped.
Note that ARCA Cap analogue has recently been discontinued. Please check current stock levels.
Unit Definition:
One unit results in an A260 of 1.0 in a 1cm light path. One unit is equivalent to approximately 50 nmoles of Cap Analogue.
Storage Buffer:
The methylated and unmethylated Cap Analogues are provided as 20mM solutions in sterile deionised water adjusted to pH 7.0.
Quality Control:
Each lot of a Cap Analogue is functionally tested as a substrate for incorporation and capping of an RNA transcript synthesised using an AmpliScribe™ T7 Transcription Kit and prescribed reaction conditions.
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