Sequence arrangement at dBP exons

Copyright information:Taken from "A class of human exons with predicted distant branch points revealed by analysis of AG dinucleotide exclusion zones"Genome Biology 2006;7(1):R1-R1.Published online 13 Jan 2006PMCID:PMC1431707.Copyright © 2006 Gooding et al.; licensee BioMed Central Ltd. The locations of several dBPs that have been mapped are shown, along with the locations of the first and second AG dinucleotides upstream of the 3'ss. In experimentally verified cases of dBP exons the BPS and PPT can be located hundreds of nucleotides upstream of the 3'ss. Because step 2 of splicing in these introns involves a scanning process from the BPS to locate the 3'ss at the first downstream AG, the region between the 3'ss and the BPS is devoid of AG dinucleotides. Upstream of the BPS, AGs appear no longer to be excluded, as indicated by the locations of second AGs upstream of the 3'ss. Here we refer to the region between the 3'ss and the first upstream AG as the AG exclusion zone (AGEZ). BPS, branch point sequence; dBP, distant branch point; PPT, polypyrimidine tract; 3'ss, 3' splice site.