Evidence for Two Pathways of Iodothyronine 5′-Deiodination in Rat Pituitary That Differ in Kinetics, Propylthiouracil Sensitivity, and Response to Hypothyroidism

• Text
• PDF

Abstract

We have studied 5′-deiodination of thyroxine (T4) and 3,3′,5′-triiodothyronine (rT3) in rat pituitary tissue in vitro, with respect to substrate specificity, reaction kinetics, effects of 6-n-propyl-2-thiouracil (PTU), and the time course of effects of thyroid hormone depletion and repletion. Removal of one phenolic iodine or both tyrosyl iodines from the T4 molecule resulted in compounds that were not deiodinated, but alterations in the alanine side chain had little effect.

Authors

Theo J. Visser, Michael M. Kaplan, Jack L. Leonard, P. Reed Larsen