5' Capping protocol to add 5’ cap structures to exogenous synthetic RNA references (spike-ins)

Abstract Exogenous spike-ins like SIRV and ERCC mixes lack the typical 7-Methylguanosine (m7G) cap structure found in natural eukaryotic RNA transcripts, rendering them incompatible with certain library preparation protocols. This method details the addition of 5’ m7G caps to these spike-ins, enabling their use as external references in cDNA library production dependent on m7G cap structures.