Photoaffinity labeling of steroid binding proteins with unmodified ligands. 1981

H M Westphal, and G Fleischmann, and M Beato

Photoactivation of the alpha,beta-unsaturated ketones of natural and synthetic steroid molecules by light of lambda greater than or equal to 330 nm allows their covalent attachment to steroid-binding proteins. The general validity of this method is demonstrated with two steroid hormone receptors and the steroid-binding protein uteroglobin. Progesterone can be covalently attached to the partially purified progesterone receptor and to uteroglobin, and comigrates with the binding proteins upon electrophoresis in polyacrylamide gels containing sodium dodecyl sulfate. Similarly the synthetic glucocorticoid triamcinolone acetonide can be covalently bound to the partially purified glucocorticoid of rat liver. This method allows the identification of steroid hormone receptors after electrophoresis in polyacrylamide gels containing sodium dodecyl sulfate. Labeling with radioactive steroids is specific since it can be prevented by the addition of an excess of non-radioactive ligand. Digestion of the labeled binding proteins with trypsin or chymotrypsin yields a defined pattern of radioactive peptides, demonstrating that covalent attachment takes place at specific binding sites.

UI MeSH Term Description Entries
D008024 Ligands A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed) Ligand
D008027 Light That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range. Light, Visible,Photoradiation,Radiation, Visible,Visible Radiation,Photoradiations,Radiations, Visible,Visible Light,Visible Radiations
D010455 Peptides Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are considered to be larger versions of peptides that can form into complex structures such as ENZYMES and RECEPTORS. Peptide,Polypeptide,Polypeptides
D010777 Photochemistry A branch of physical chemistry which studies chemical reactions, isomerization and physical behavior that may occur under the influence of visible and/or ultraviolet light. Photochemistries
D011980 Receptors, Progesterone Specific proteins found in or on cells of progesterone target tissues that specifically combine with progesterone. The cytosol progesterone-receptor complex then associates with the nucleic acids to initiate protein synthesis. There are two kinds of progesterone receptors, A and B. Both are induced by estrogen and have short half-lives. Progesterone Receptors,Progestin Receptor,Progestin Receptors,Receptor, Progesterone,Receptors, Progestin,Progesterone Receptor,Receptor, Progestin
D011987 Receptors, Steroid Proteins found usually in the cytoplasm or nucleus that specifically bind steroid hormones and trigger changes influencing the behavior of cells. The steroid receptor-steroid hormone complex regulates the transcription of specific genes. Corticosteroid Receptors,Receptors, Corticosteroid,Steroid Receptors,Corticosteroid Receptor,Receptors, Steroids,Steroid Receptor,Receptor, Corticosteroid,Receptor, Steroid,Steroids Receptors
D006023 Glycoproteins Conjugated protein-carbohydrate compounds including MUCINS; mucoid, and AMYLOID glycoproteins. C-Glycosylated Proteins,Glycosylated Protein,Glycosylated Proteins,N-Glycosylated Proteins,O-Glycosylated Proteins,Glycoprotein,Neoglycoproteins,Protein, Glycosylated,Proteins, C-Glycosylated,Proteins, Glycosylated,Proteins, N-Glycosylated,Proteins, O-Glycosylated
D000345 Affinity Labels Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors. These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids. Affinity Labeling Reagents,Labeling Reagents, Affinity,Labels, Affinity,Reagents, Affinity Labeling
D014598 Uteroglobin A steroid-inducible protein that was originally identified in uterine fluid. It is a secreted homodimeric protein with identical 70-amino acid subunits that are joined in an antiparallel orientation by two disulfide bridges. A variety of activities are associated with uteroglobin including the sequestering of hydrophobic ligands and the inhibition of SECRETORY PHOSPHOLIPASE A2. Blastokinin,Clara Cell Secretory Protein,Clara Cell-Specific Protein,Secretoglobin, Family 1A, Member 1,Clara Cell Specific Protein

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