Across-paralog comparison of the exon patterns for Cpeb1. The numbers represent the lengths of exons in a sequential order. The locations and size of exons were determined by aligning the cDNA sequence to the genomic sequence. For simplicity, only one RefSeq sequence is used for each organism. The patterns in C. elegans and Drosophila are not consistent with those in the vertebrates. However the patterns among the vertebrates are highly conserved. The asterisk represents the variable region of ±15-nt discussed in the text, which would subsequently lead to 5-aa deletion or insertion.