Effect of thyroid hormone binding proteins on insulin receptor binding of B1-thyronine-insulin analogues.

Certain thyronine-insulin analogues, which form non-covalent complexes with plasma proteins, have been shown to act preferentially in the liver. We hypothesized that this property may be dependent on the ability of the analogue to bind to the insulin receptor without prior dissociation from the binding protein. NaB1-L-thyroxyl-insulin, NaB1-3,3',5'-triiodothyronine-insulin, NaB1-D-thyroxyl-insulin and NaB1-L-thyroxyl-aminolauroyl-insulin were compared with insulin for their capacity to inhibit the binding of [125I]TyrA14-insulin to rat liver plasma membrane in albumin-free buffer.