15 KDa Selenoprotein （SEP15） is a protein-coding gene which contains a selenocysteine （Sec） residue at its active site. The selenocysteine is encoded by the UGA codon that usually signals translation termination. The 3’ UTR of selenoprotein genes have a conventional stem-loop structure， the sec insertion sequence （SECIS）， which is necessary for the recognition of UGA as a Sec codon rather than as a stop signal. Studies in mouse propose that this selenoprotein may have redox function and may be implicated in the quality control of protein folding. This gene is localized on chromosome 1p31， a genetic locus usually mutated or deleted in human cancers.Diseases associated with SEP15 include lung cancer susceptibility， and chronic lymphocytic leukemia.
