Different types of exons used to assemble selenoprotein genes. A. c-exons in which no in-frame TGA codon is allowed. B. i-exons in which an in-frame TGA codon is present and codes for a Sec residue. The signals such as splice sites AG and GT, start codon and stop codons are indicated in the figure.
Jiang et al. BMC Genomics 2010 11:289 doi:10.1186/1471-2164-11-289