Purification of chick nuclear thyroid-hormone-receptor protein

Area of Science:

• Biochemistry
• Molecular Biology
• Endocrinology

Background:

• Nuclear thyroid-hormone receptors are crucial for regulating gene expression.
• Previous methods for receptor purification were often inefficient.
• Chick liver chromatin proteins offer a source for studying these receptors.

Purpose of the Study:

• To develop an efficient method for purifying thyroid-hormone-receptor proteins.
• To characterize the purified receptor protein.

Main Methods:

• Ammonium sulfate fractionation of chick liver chromatin proteins.
• Affinity chromatography using a specialized Sepharose ether medium.
• Hydroxymercuribenzoic acid treatment to facilitate receptor-hormone complex dissociation.

Main Results:

• A crude receptor preparation exhibiting high affinity for triiodothyronine and thyroxine was obtained.
• Hydroxymercuribenzoic acid significantly enhanced the dissociation rate of the receptor-hormone complex at low temperatures.
• A purified receptor fraction (1000-10000-fold) with a molecular mass of approximately 65 kDa was achieved, retaining binding activity.

Conclusions:

• Affinity chromatography coupled with hydroxymercuribenzoate treatment provides an effective method for purifying thyroid-hormone receptors.
• The purified 65 kDa protein retains significant thyroid hormone-binding activity.
• This method offers a substantial improvement in receptor purification efficiency.