Specific binding sites for 3,3′-T2can 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 (Ka) and the binding capacity were on average 0.5 × 108M-1and 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′-T2binding, examined in competition studies, followed this order: 3,3′-T2> 3,5-T2> rT3. The other iodothyronines (3′,5′-T2, T3, T4, 3-T1, 3′-T1, 3,5-Diac and 3,3′-Diac) showed only a small competition or none at all. © 1994.
SPECIFIC BINDING-SITES FOR 3,3'-DIIODO-L-THYRONINE (3,3'-T-2) IN RAT-LIVER MITOCHONDRIA
LANNI, Antonia;
1994
Abstract
Specific binding sites for 3,3′-T2can 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 (Ka) and the binding capacity were on average 0.5 × 108M-1and 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′-T2binding, examined in competition studies, followed this order: 3,3′-T2> 3,5-T2> rT3. The other iodothyronines (3′,5′-T2, T3, T4, 3-T1, 3′-T1, 3,5-Diac and 3,3′-Diac) showed only a small competition or none at all. © 1994.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
