Biomaterial Database

Phosphorylation of RNA polymerase I-associated polypeptides of Tetrahymena pyriformis. 1987

M Freiburg

In the ciliate Tetrahymena pyriformis phosphorylation of RNA polymerase I [EC 2.7.7.6] and of polymerase-associated polypeptides was investigated in growing and growth-arrested cultures which differ widely in their rates of rRNA synthesis. Several putative subunits of RNA polymerase I (of 180, 21.5, and 19.5 kDa) and a polymerase-associated polypeptide of 27 kDa were found to be phosphorylated, independent of the growth conditions. However, an additional enzyme-associated polypeptide of 26 kDa was intensively labeled with 32P only after arrestment of growth by starvation. The molar quantities of both phosphorylated, enzyme-associated polypeptides thereby did not differ in growing and growth-arrested cultures, and the specific 32P-labeling of cellular ATP remained nearly unchanged under the different culture conditions. These findings indicate a selective, reversible phosphorylation of the RNA polymerase I-associated 26 kDa polypeptide correlated with conditions of repressed rRNA synthesis induced by the starvation procedure. In vitro phosphorylation in macronuclei isolated from growing and growth-arrested cultures using [gamma-32P]ATP revealed essentially the same pattern of labeling of the enzyme-associated polypeptides of 27 and 26 kDa as it was found in vivo.

UI	MeSH Term	Description	Entries
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
D010766	Phosphorylation	The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.	Phosphorylations
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
D002499	Centrifugation, Density Gradient	Separation of particles according to density by employing a gradient of varying densities. At equilibrium each particle settles in the gradient at a point equal to its density. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Centrifugations, Density Gradient,Density Gradient Centrifugation,Density Gradient Centrifugations,Gradient Centrifugation, Density,Gradient Centrifugations, Density
D000255	Adenosine Triphosphate	An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.	ATP,Adenosine Triphosphate, Calcium Salt,Adenosine Triphosphate, Chromium Salt,Adenosine Triphosphate, Magnesium Salt,Adenosine Triphosphate, Manganese Salt,Adenylpyrophosphate,CaATP,CrATP,Manganese Adenosine Triphosphate,MgATP,MnATP,ATP-MgCl2,Adenosine Triphosphate, Chromium Ammonium Salt,Adenosine Triphosphate, Magnesium Chloride,Atriphos,Chromium Adenosine Triphosphate,Cr(H2O)4 ATP,Magnesium Adenosine Triphosphate,Striadyne,ATP MgCl2
D012318	RNA Polymerase I	A DNA-dependent RNA polymerase present in bacterial, plant, and animal cells. The enzyme functions in the nucleolar structure and transcribes DNA into RNA. It has different requirements for cations and salts than RNA polymerase II and III and is not inhibited by alpha-amanitin.	DNA-Dependent RNA Polymerase I,RNA Polymerase A,DNA Dependent RNA Polymerase I,Polymerase A, RNA,Polymerase I, RNA
D013769	Tetrahymena pyriformis	A species of ciliate protozoa used extensively in genetic research.	Tetrahymena pyriformi,pyriformi, Tetrahymena