title: A radioimmunoassay for type I iodothyronine 5'-monodeiodinase in human tissues.
abstract: We have developed a sensitive, specific and reproducible radioimmunoassay (RIA) for measurement of human type I monodeiodinase (5'-DI) protein. Anti-5'-DI antibody was produced by immunization of rabbits with a conjugate of bovine serum albumin and a 16 amino acid synthetic peptide, corresponding to a portion of the carboxy-terminal region of the human 5'-DI (PI-99). In a final dilution of 1:500, our anti-5'-DI antibody bound about 30%-35% of a tracer amount of 125I-PI-99. The detection threshold of the RIA approximated 0.4 pmol PI-99 or an equivalent amount of 0.4 pmol 5'-DI. The coefficient of variation averaged 5% within an assay and 14% between assays. Dose-response curves of tissue proteins were essentially parallel to that of PI-99. In a total number of 35 normal human tissue samples, the mean (+/- standard deviation [SD], picomole per milligram of protein [pmol]) 5'-DI content was 25 +/- 6.7 in kidney, it was significantly lower (p < 0.05) in liver at 3.9 +/- 1.1, 2.8 +/- 0.8 in intestine, 2.3 +/- 0.98 in adrenal, 4.2 +/- 2.5 in skeletal muscle, 3.8 +/- 1.4 in heart and 2.6 +/- 2.4 in thyroid; it was 1.4 +/- 0.3 in Graves' thyroid. Our data suggest that (1) 5'-DI is distributed widely among human tissues; (2) kidney is the tissue most enriched with 5'-DI; (3) 5'-DI content in the thyroid is not increased in Graves' disease.
authors.affiliation: Unità di Neuroendocrinologia Cardiovascolare, Istituto di Fisiologia Clinica CNR, Pisa, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Sabatino
authors.forename: I J
authors.initials: IJ
authors.lastname: Chopra
authors.forename: S
authors.initials: S
authors.lastname: Tanavoli
authors.forename: P
authors.initials: P
authors.lastname: Iacconi
authors.forename: G
authors.initials: G
authors.lastname: Iervasi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003429:Cross Reactions; D006111:Graves Disease / Q000201:enzymology; D006801:Humans; D007201:Indicator Dilution Techniques; D007453:Iodide Peroxidase / Q000378:metabolism*; D008875:Middle Aged; D011863:Radioimmunoassay / Q000379:methods* / Q000592:standards; D012016:Reference Values; D012680:Sensitivity and Specificity; D014018:Tissue Distribution
chemical_list: C109812:iodothyronine deiodinase type I; D007453:Iodide Peroxidase