15 kDa selenoprotein is a protein that in humans is encoded by the SEP15gene.[5] Two alternatively spliced transcript variants encoding distinct isoforms have been found for this gene.
Function
This gene encodes a selenoprotein, which contains a selenocysteine (Sec) residue at its active site. The selenocysteine is encoded by the UGAcodon that normally signals translation termination. The 3' UTR 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. Studies in mouse suggest that this selenoprotein may have redox function and may be involved in the quality control of protein folding.[5]
Clinical significance
This gene is localized on chromosome 1p31, a genetic locus commonly mutated or deleted in human cancers.[5]
Recent studies have shown in mice, where the SEP15 gene has been silenced the mice subsequently became deficient in SEP15 and were able to inhibit the development of colorectal cancer.[7]
Structure
The particular structure has an alpha/beta central domain which is actually made up of three alpha helices and a mixed parallel/anti-parallel four-stranded beta-sheet.[6]
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Kumaraswamy E, Korotkov KV, Diamond AM, Gladyshev VN, Hatfield DL (2002). "Genetic and functional analysis of mammalian Sep15 selenoprotein". Protein Sensors and Reactive Oxygen Species - Part A: Selenoproteins and Thioredoxin. Methods in Enzymology. Vol. 347. pp. 187–97. doi:10.1016/S0076-6879(02)47017-6. ISBN978-0-12-182248-4. PMID11898406.
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