Schematic of the strategy for surface immobilisation of large RNAs.

<p>RNA (brown) is prepared by <i>in vitro</i> transcription and terminated by template run-off, from the corresponding DNA template (grey); the RNA incorporated between four and eight adenines at the 3′ end. A biotinylated uridine (U-biotin, filled black circle) is then ligated onto the 3′ poly-A-tail RNA by T4 RNA ligase. Excess U-biotin was then removed from the labelled RNA using a size exclusion spin column leaving it ready for sensor surface immobilisation. Following immobilisation of the biotin-labelled RNA to a streptavidin sensor surface (yellow), interactions of binding partner molecules (green) with the immobilised RNA can then be undertaken by on-slide probing or SPR analysis. A schematic sensorgram illustrative of a binding event for SPR immobilisation is shown.