3NSelP of Amphioxus. A. The gene structure of 3NSelP with all Sec-TGA codons and SECIS elements is indicated. R1, R2, and R3 represent the 3-repeat regions. Each of the repeated regions can be divided into several parts and labeled parts a, b, c, and d. B. Multiple alignment 3-repeat region of the 3NSelP Sec residues and part a, b, c, and d are shown. C. The secondary structures of the two SECIS elements of the 3NSelP gene are shown.