title: Lysosomal thyroid hormone 5'-deiodinase.
abstract: Lysosomes prepared from rat liver and kidney after loading with the detergent Triton WR-1339 show membrane-bound 5'-deiodinase activity with marked specificity for 3,3',5'-triiodothyronine (reverse T3), lesser activity with respect to thyroxine (T4) and almost none towards 3,3',5'-triiodothyronine (T3). The enzyme is thiol dependent and shows maximal catalysis at pH 7.2. As many of the states known to alter thyroid hormone levels also affect lysosomal function, inhibition of the lysosomal 5'-deiodinase leading to an increase in intracellular reverse T3 may be an initiating mechanism for thyroid hormone change.
mesh_terms: D000818:Animals; D002458:Cell Fractionation; D003902:Detergents; D007453:Iodide Peroxidase / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008247:Lysosomes / Q000201:enzymology*; D010544:Peroxidases / Q000378:metabolism*; D011092:Polyethylene Glycols; D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology; D013379:Substrate Specificity
chemical_list: D003902:Detergents; D011092:Polyethylene Glycols; D010544:Peroxidases; D007453:Iodide Peroxidase; C016811:tyloxapol