Figure 6From: Origin and evolution of spliceosomal intronsFractions of protosplice sites and actual introns in the three phases. Species abbreviations: (At) green plant Arabidopsis thaliana, (Hs) human Homo sapiens. An excess of protosplice sites in phase 0 is noticeable, however the ‘protosplice site’ hypothesis, which posits that introns are randomly inserted into protosplice sites, is unable to fully explain the observed over-representation of phase 0 introns. The data is from [125, 132].Back to article page