Biomaterial Database

A specific L-tri-iodothyronine-binding protein in the cytosol fraction of human breast adipose tissue. 1982

M L Rao, and G S Rao

1. Binding of l-tri-[(125)I]iodothyronine to the cytosol fraction of normal human female breast adipose tissue was investigated by the charcoal adsorption method. Equilibrium of binding was reached after 120s at 25 degrees C. 2. The l-tri-[(125)I]iodothyronine-binding component is a protein; this was confirmed by experiments in which binding was totally lost after heating the cytosol fraction for 10min at 100 degrees C and in which binding was diminished after treatment with proteolytic enzymes and with thiol-group-blocking reagents. The binding protein was stable at -38 degrees C for several months. 3. It displayed saturability, high affinity (apparent K(d) 3.28nm) and a single class of binding sites. 4. High specificity for l-tri-iodothyronine and l-3,5-di-iodo-3'-isopropylthyronine was observed, whereas other iodothyronines were less effective in displacing l-tri-[(125)I]-iodothyronine from its binding site. 5. The binding of the hormone by the cytosol fraction did not show a pH optimum. 6. When cytosol fractions of adipose tissue from different females were subjected to radioimmunoassay for the determination of thyroxine-binding globulin a value of 0.304+/-0.11mug/mg of cytosol protein (mean+/-s.d., n=4) was obtained; the mean concentration in plasma was 0.309+/-0.07mug/mg of plasma protein (mean+/-s.d., n=3). 7. The K(a) value of 6.3x10(8)m(-1) of l-tri-[(125)I]iodothyronine for binding to plasma, the similar thermalinactivation profiles of binding and the reactivity to thiol-group-blocking reagents were some properties common between the binding components from the cytosol fraction and plasma. 8. These results suggest that the cytosol fraction of human female breast adipose tissue contains thyroxine-binding globulin; the protein that binds l-tri-[(125)I]iodothyronine with high affinity and specificity appears to be similar to thyroxine-binding globulin.

UI	MeSH Term	Description	Entries
D011956	Receptors, Cell Surface	Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.	Cell Surface Receptor,Cell Surface Receptors,Hormone Receptors, Cell Surface,Receptors, Endogenous Substances,Cell Surface Hormone Receptors,Endogenous Substances Receptors,Receptor, Cell Surface,Surface Receptor, Cell
D011988	Receptors, Thyroid Hormone	Specific high affinity binding proteins for THYROID HORMONES in target cells. They are usually found in the nucleus and regulate DNA transcription. These receptors are activated by hormones that leads to transcription, cell differentiation, and growth suppression. Thyroid hormone receptors are encoded by two genes (GENES, ERBA): erbA-alpha and erbA-beta for alpha and beta thyroid hormone receptors, respectively.	Diiodotyrosine Receptors,Receptors, Diiodotyrosine,Receptors, Thyroxine,Receptors, Triiodothyronine,T3 Receptors,T4 Receptors,Thyroid Hormone Receptors,Thyroxine Receptors,Triiodothyronine Receptors,DIT Receptors,Diiodotyrosine Receptor,MIT Receptors,Monoiodotyrosine Receptors,Receptors, DIT,Receptors, MIT,Receptors, Monoiodotyrosine,Receptors, T3,Receptors, T4,T3 Receptor,T4 Receptor,Thyroid Hormone Receptor,Thyroxine Receptor
D001940	Breast	In humans, one of the paired regions in the anterior portion of the THORAX. The breasts consist of the MAMMARY GLANDS, the SKIN, the MUSCLES, the ADIPOSE TISSUE, and the CONNECTIVE TISSUES.	Breasts
D003600	Cytosol	Intracellular fluid from the cytoplasm after removal of ORGANELLES and other insoluble cytoplasmic components.	Cytosols
D005260	Female		Females
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000273	Adipose Tissue	Specialized connective tissue composed of fat cells (ADIPOCYTES). It is the site of stored FATS, usually in the form of TRIGLYCERIDES. In mammals, there are two types of adipose tissue, the WHITE FAT and the BROWN FAT. Their relative distributions vary in different species with most adipose tissue being white.	Fatty Tissue,Body Fat,Fat Pad,Fat Pads,Pad, Fat,Pads, Fat,Tissue, Adipose,Tissue, Fatty
D013237	Stereoisomerism	The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)	Molecular Stereochemistry,Stereoisomers,Stereochemistry, Molecular,Stereoisomer
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures
D013970	Thyronines	A group of metabolites derived from THYROXINE and TRIIODOTHYRONINE via the peripheral enzymatic removal of iodines from the thyroxine nucleus. Thyronine is the thyroxine nucleus devoid of its four iodine atoms.	Thyronine