Selenoproteins contain the amino acid selenocysteine (sec), which is encoded by UGA, normally a termination codon. Selenoproteins have a wide range of cellular functions including regulation of selenium transport, thyroid hormones, immunity, and redox homeostasis. SECISBP2 binds a sec insertion sequence (SECIS) in the 3-prime UTRs of selenoprotein mRNAs, permitting decoding of UGA as sec. SECISBP2L shares significant similarity with SECISBP2 and binds SECIS-containing sequences, but it lacks the ability to catalyze incorporation of sec into proteins. SECISBP2L binds SECIS (Sec insertion sequence) elements present on selenocysteine (Sec) protein mRNAs, but does not promote Sec incorporation into selenoproteins in vitro.