T₃ Binding Properties of Nuclear Fibroblast Receptors from Patients Homozygous and Heterozygous for A Dominant Negative Mutation of C-erbAβ

Abstract

This study represents the first measurements of T₃ binding to nuclear receptors in fibroblasts from a homozygous child with a dominant negative thyroid hormone receptor gene. Previously demonstrated in this child and kindred was a three base pair deletion in the c-erbAβ thyroid hormone receptor gene resulting in the loss of threonine codon 332. In this study using cultured skin fibroblasts from this homozygous child and his heterozygous father there was normal binding affinity and a two-fold less binding capacity in comparison to control fibroblasts. These data are consistent with loss of β-receptor T₃-binding activity, but the presence of normally functioning α-receptors in vivo.