Rat liver nuclear receptors for thyroid hormone: binding characteristics after stabilization and storage

Conditions for both stabilization and storage of rat liver nuclear receptors for thyroid hormone for up to 28 days were determined using agents that might protect the receptor from spontaneous degradation. Without any protective agent a statistically significant (P < 0.05) diminution of 3,5,3'-triiodothyronine (T3) binding occurred at 0 degree C within 14 days. Dithiothreitol can maintain the initial T3 maximum binding capacity (MBC) for up to 7 days at 0 degree C. The compounds tested, including spermine, sodium molybdate, thioglycerol, and nitrogen gas, had no stabilization effect on nuclear receptors. A statistically significant (P < 0.05) stabilization for up to 28 days at 0 degree C of the initial MBC of T3 receptors was observed in the presence of 0.2 mol.l-1 phosphate anion or 20% (w/w) glycerol. The protective effect of phosphate anion was due to the phosphate ion itself rather than to the high ionic strength.