Figure 7

Prevalence of alternative splicing as a function of AGEZ size. For both plots, acceptor sites were excluded from consideration if there was another acceptor site ≤ 40 nucleotides upstream (see Materials and methods). In order to constrain the domain of the plots, all AGEZ values greater than 300 nucleotides were taken as 300 nucleotides. For both plots the standard error was calculated as sqrt(r·(n - r)/n), with n being the total number of acceptor sites/introns in the group, and r being the number of these seen to undergo alternative splicing of the defined type. See Materials and methods for further details. (a) Frequency of observed cassette exon alternative splicing as a function of the AGEZ for considered acceptor sites. The overall average is 19.8% (red line). The three data points representing AGEZ ≥ 150 nucleotides correspond to 197 exons with an average 32.5% observed cassette alternative exons. (b) Frequency of observed 3' splice site exon isoform alternative splicing as a function of the AGEZ for considered acceptor sites. The overall average is 9.6% (red line), with the first data point representing 8,657 exons having AGEZ values between 12 and 19 inclusive, and with 15.1% of these having observed acceptor site isoforms (intriguingly these are not a consequence of examining the downstream of two closely spaced acceptor sites because these have been excluded). AGEZ, AG exclusion zone.