Complex sentence: In 2007, the UGA codon was identified as the codon coding for Selenocysteine (Sec) and found in 25 selenoproteins located in the active site of the protein.
Split into simpler sentences: In 2007, the UGA codon was identified as the codon coding for Selenocysteine (Sec). This amino acid is found in 25 selenoproteins where it is located in the active site of the protein.