Hepatic iodothyronine 5'-deiodinase. The role of selenium.
Selenium (Se) deficiency decreased by 8-fold the activity of type 1 iodothyronine 5'-deiodinase (ID-I) in hepatic microsomal fractions from rats. Solubilized hepatic microsomes from rats injected with 75Se-labelled Na2SeO3 4 days before killing were found by chromatography on agarose gels to contain a 75Se-containing fraction with ID-I activity. PAGE of this fraction under reducing conditions, followed by autoradiography, revealed a single 75Se-containing protein (Mr 27,400 +/- 300). This protein could also be labelled with 125I-bromoacetyl reverse tri-iodothyronine, an affinity label for ID-I. The results suggest that hepatic ID-I is a selenoprotein or has an Se-containing subunit essential for activity.
Arthur
J R
JR
Division of Biochemical Sciences, Rowett Research Institute, Bucksburn, Aberdeen, U.K.
Nicol
F
F
Beckett
G J
GJ
D000818:Animals; D002852:Chromatography, Ion Exchange; D004032:Diet; D004591:Electrophoresis, Polyacrylamide Gel; D007453:Iodide Peroxidase / Q000302:isolation & purification / Q000378:metabolism*; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains; D012643:Selenium / Q000172:deficiency / Q000494:pharmacology*
D007527:Isoenzymes; D007453:Iodide Peroxidase; D012643:Selenium