Expression and characterization of nonmammalian selenoprotein P in the zebrafish, Danio rerio.
BACKGROUND
Selenoprotein P is a protein of considerable intrigue, due to its unusual composition and requirements for its biosynthesis. Whereas most selenoproteins contain a single selenocysteine residue, the human, bovine and rodent selenoprotein P genes encode proteins containing 10-12 selenocysteines. Selenoprotein P genes have, to date, only been reported in mammals, and the function of the protein remains elusive.


RESULTS
Herein, we report the identification and characterization of nonmammalian selenoprotein P in the zebrafish Danio rerio. Sequencing of the cDNA revealed the presence of 17 selenocysteine codons, the highest number reported in any protein. Two histidine-rich regions present in the mammalian selenoprotein P sequences are conserved in the zebrafish protein, and two SECIS elements are present in the 3' untranslated region. Whole-mount in situ hybridization of zebrafish embryos revealed high levels of expression of selenoprotein P mRNA in fertilized eggs and in the yolk sac of developing embryos. Transient transfection of the cDNA in mammalian cells resulted in efficient expression of the full-length secreted selenoprotein. A single N-glycosylation site is predicted, and shown to be utilized.


CONCLUSIONS
Discovery of selenoprotein P in the zebrafish opens a previously unavailable avenue for genetic investigation of the functions of this unusual protein.
Tujebajeva
R M
RM
Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
Ransom
D G
DG
Harney
J W
JW
Berry
M J
MJ
D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D002460:Cell Line; D015870:Gene Expression; D006031:Glycosylation; D006801:Humans; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009928:Organ Specificity; D020161:Physical Chromosome Mapping; D014176:Protein Biosynthesis; D011506:Proteins / Q000737:chemistry / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis; D012644:Selenium Radioisotopes; D051149:Selenoprotein P; D051140:Selenoproteins; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D015027:Zebrafish; D029961:Zebrafish Proteins
D011506:Proteins; D012333:RNA, Messenger; D012644:Selenium Radioisotopes; D051149:Selenoprotein P; D051140:Selenoproteins; D029961:Zebrafish Proteins; C495236:selenop protein, zebrafish; C495237:selenop2 protein, zebrafish