Fig. 2

Transcript heterogeneity. This figure illustrates the structure of various transcripts observed at very low levels (less than 10 transcripts per dataset) all of which initiate at the transcription start site that drives expression of the S glycoprotein. For orientation, the structure of the dominant S glycoprotein transcript is shown in red in the examples selected from the MRC5 dataset. Three sets of example transcripts are shown from MRC5, A549 and HEK293 cells. The transcripts shown arise from splicing events that utilise only the canonical GU-AG splice donor/acceptor pair present in over 90% of eukaryotic splicing events. As can be seen, some of the transcripts arise from unintended splice site usage as well as from missing the intended BGH polyadenylation signal and utlilising other polyadenylation signals further down the vector genome