Selenoprotein T (SELT)

Selenoproteins, such as SELT, contain the rare twenty-first amino acid, selenocysteine (sec). These proteins lack common amino acid sequence motifs, but the 3-prime untranslated regions of selenoprotein genes have a common stem-loop structure, the sec insertion sequence (SECIS), that is necessary for the recognition of UGA as a sec codon rather than as a stop signal. The deduced 163-amino acid SELT protein has a calculated molecular mass of about 19 kD. The selenocysteine residue, sec17, is encoded by TGA and is located in the N-terminal portion of the protein. The SECIS element is located 509 nucleotides downstream of the sec17 codon. Sec17 is preceded by a conserved cys14 in a putative redox center, CxxU, similar to that found in several redox active proteins.