Figure 2.

Splicing signals, recognition models and splicing regulatory elements. The core splicing signals within pre-mRNA and their consensus sequences are schematically illustrated (A). N, any purine or pyrimidine; Y, any pyrimidine; Pu-rich, purine-rich element. (B) The recognition models of spliceosome include “Exon Definition” and “Intron Definition”. The locations and roles of splicing regulatory elements are shown in (C), for which the three-letter abbreviations are stated in the main text. BP—branch point; PPT—polypyrimidine tract; ESS—exonic splicing silencers; ISS—intronic splicing silencers; ESE—exonic splicing enhancers; ISE—intronic splicing enhancers.