Specific binding sites for 3,3′-diiodo- l -thyronine (3,3′-T 2 ) in rat liver mitochondria
1994; Wiley; Volume: 351; Issue: 2 Linguagem: Inglês
10.1016/0014-5793(94)00840-x
ISSN1873-3468
AutoresAntonia Lanni, María Moreno, C Horst, Assunta Lombardi, G. Noriega Fernando,
Tópico(s)Thyroid Disorders and Treatments
ResumoSpecific binding sites for 3,3′‐T 2 can be detected in swollen and osmotically treated mitochondria (OTM) from normal and hypothyroid rat liver. In hypothyroid animals, maximal values of binding were obtained at 0°C and 20°C while values were lower at 37°C and no specific binding could be observed at 60°C. Binding was maximal at pH 6.4 and the mean values for the apparent association constant ( K a ) and the binding capacity were on average 0.5 × 10 8 M −1 and 2.4 pmol/mg mitochondrial protein, respectively. No differences were observed between normal and hypothyroid rats with the exception of the capacity that was higher in normal animals (5.5 pmol/mg mitochondrial protein). The specificity of 3,3′‐T 2 binding, examined in competition studies, followed this order: 3,3′‐T 2 > 3,5‐T 2 > rT 3 . The other iodothyronines (3′,5′‐T 2 , T 3 , T 4 , 3‐T 1 , 3′‐T 1 , 3,5‐Diac and 3,3′‐Diac) showed only a small competition or none at all.
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