Biomaterial Database

Identification of the amatoxin-binding subunit of RNA polymerase B by affinity labeling experiments. Subunit B3-the true amatoxin receptor protein of multiple RNA polymerase B. 1976

O G Brodner, and T Wieland

Crude calf thymus DNA-dependent RNA polymerase, RNA polymerase B (ribonucleoside triphosphate: RNA nucleotidyltransferase, EC 2.7.7.6), was incubated with the tritium labeled, potent inhibitor [3H]amanin, in order to form the enzymatically inactive [3H]amanin-polymerase complex ([3H]A-P complex). Subsequent purification procedures for the [3H]A-P complex were based on radioactive assays. Phosphocellulose chromatography separated two radioactive components: PCI, the previously reported amatoxin binding protein, ABP (Brodner and Wieland, 1976), and PC II, the [3H]A-P complex. Sodium dodecyl sulfate gel electrophoresis of the complex showed the presence of a new heavy band very close to subunit B 1 and a decreased intensity of subunit band B 3. These were the only differences noted in the subunit structure of RNA polymerase B. [3H]Amanin was covalently coupled to the enzyme, affinity labeling, by a water-soluble carbodiimide and the resultant conjugate submitted to sodium dodecyl sulfate gel electrophoresis. The profile of radioactivity showed one main peak (greater than 2000 cpm) coinciding with the 550-nm absorption peak of subunit B 3 on a stained parallel gel. Since no other protein band contains any significant radioactivity, the binding site for [3H]amanin and most probably for all amatoxins is localized on the B 3 subunit SB 3.

UI	MeSH Term	Description	Entries
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D009183	Mycotoxins	Toxic compounds produced by FUNGI.	Fungal Toxins,Mycotoxin,Toxins, Fungal
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011955	Receptors, Drug	Proteins that bind specific drugs with high affinity and trigger intracellular changes influencing the behavior of cells. Drug receptors are generally thought to be receptors for some endogenous substance not otherwise specified.	Drug Receptors,Drug Receptor,Receptor, Drug
D002417	Cattle	Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.	Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D002846	Chromatography, Affinity	A chromatographic technique that utilizes the ability of biological molecules, often ANTIBODIES, to bind to certain ligands specifically and reversibly. It is used in protein biochemistry. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Chromatography, Bioaffinity,Immunochromatography,Affinity Chromatography,Bioaffinity Chromatography
D004591	Electrophoresis, Polyacrylamide Gel	Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.	Polyacrylamide Gel Electrophoresis,SDS-PAGE,Sodium Dodecyl Sulfate-PAGE,Gel Electrophoresis, Polyacrylamide,SDS PAGE,Sodium Dodecyl Sulfate PAGE,Sodium Dodecyl Sulfate-PAGEs
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
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining