Biomaterial Database

Purification and DNA-binding properties of the catabolite gene activator protein. 1971

A D Riggs, and G Reiness, and G Zubay

A protein required for the activation of the lac operon has been extensively purified and partly characterized. This protein, called CGA protein (catabolite gene activator protein, sometimes named CAP), is a dimer with subunits of 22,000 daltons. Purified CGA protein has a substantial affinity for DNA; this affinity is greatly strengthened by cAMP and strongly inhibited by cGMP. Other studies have shown that these cyclic nucleotides compete for a binding site on CGA protein. The opposing effects of the two cyclic compounds in DNA-CGA protein binding show a parallel behavior to their effects on the expression of the lac operon. Thus cAMP, in addition to CGA protein, is required for expression of the lac operon, whereas cGMP inhibits the expression. The obvious inference is that CGA protein activates the lac operon by binding to the DNA under the influence of cAMP. Thus, CGA protein seems to be a new type of regulatory protein: a DNA-binding activator.

UI	MeSH Term	Description	Entries
D008967	Molecular Biology	A discipline concerned with studying biological phenomena in terms of the chemical and physical interactions of molecules.	Biochemical Genetics,Biology, Molecular,Genetics, Biochemical,Genetics, Molecular,Molecular Genetics,Biochemical Genetic,Genetic, Biochemical,Genetic, Molecular,Molecular Genetic
D009876	Operon	In bacteria, a group of metabolically related genes, with a common promoter, whose transcription into a single polycistronic MESSENGER RNA is under the control of an OPERATOR REGION.	Operons
D010759	Phosphorus Isotopes	Stable phosphorus atoms that have the same atomic number as the element phosphorus, but differ in atomic weight. P-31 is a stable phosphorus isotope.	Isotopes, Phosphorus
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
D002498	Centrifugation	Process of using a rotating machine to generate centrifugal force to separate substances of different densities, remove moisture, or simulate gravitational effects. It employs a large motor-driven apparatus with a long arm, at the end of which human and animal subjects, biological specimens, or equipment can be revolved and rotated at various speeds to study gravitational effects. (From Websters, 10th ed; McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
D002848	Chromatography, DEAE-Cellulose	A type of ion exchange chromatography using diethylaminoethyl cellulose (DEAE-CELLULOSE) as a positively charged resin. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	DEAE-Cellulose Chromatography,Chromatography, DEAE Cellulose,DEAE Cellulose Chromatography
D004247	DNA	A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).	DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D004589	Electrophoresis, Disc	Electrophoresis in which discontinuities in both the voltage and pH gradients are introduced by using buffers of different composition and pH in the different parts of the gel column. The term 'disc' was originally used as an abbreviation for 'discontinuous' referring to the buffers employed, and does not have anything to do with the shape of the separated zones.	Electrophoresis, Disk,Disc Electrophoresis,Disk Electrophoresis
D004790	Enzyme Induction	An increase in the rate of synthesis of an enzyme due to the presence of an inducer which acts to derepress the gene responsible for enzyme synthesis.	Induction, Enzyme
D004794	Enzyme Repression	The interference in synthesis of an enzyme due to the elevated level of an effector substance, usually a metabolite, whose presence would cause depression of the gene responsible for enzyme synthesis.	Repression, Enzyme