N-methylation of the heterogeneous nuclear ribonucleoproteins in HeLa cells
Several of the core proteins on the 40S heterogeneous nuclear ribonucleoprotein particles (hnRNP) from HeLa cells contain N/sup G/,N/sup G/-dimethyl-L-arginine (uDMA). 3-deazaadenosine (c/sup 3/Ado), an inhibitor of and substrate for s-adenosyl-L-homocysteine hydrolase, has been used to study the methylation patterns of the individual polypeptides. Trimethyllysine and uDMA formation in total cellular protein were inhibited in the presence of the drug while other methylated basic amino acids were unaffected. This inhibition was reversed within 60 min after removal of the drug from the medium. Monolayer HeLa cultures were incubated with (methyl-/sup 3/H)-L-methoinine for 12 hours in the presence of 50 uM c/sup 3/Ado. Purified particles were obtained by centrifugation of nuclear extracts on sucrose density gradients. The core proteins were isolated by two-dimensional gel electrophoresis, acid hydrolyzed and analyzed for radioactivity incorporated into methionine and methylated basic amino acids. The ratio of radioactivity incorporated into uDMA relative to that into methionine for the two major particle proteins with molecular weights of 31,000 (A/sub 1/) and 43,000 (A/sub 2/) was about 2.0 and 0.2 in control cultures. In the presence of c/sup 3/Ado, these ratios were depressed 60 to 80%. Results of pulse-chase experiments suggested that A/sub 1/ and A/sub 2/ are metabolically stable proteins (t/sub 0.5/ > 75 hr), whether or not the proteins were undermethylated. Monomethyl-L-arginine may be a precursor in the formation of u-DMA.
- Research Organization:
- Pittsburgh Univ., PA (USA)
- OSTI ID:
- 5023171
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NUCLEOPROTEINS
METHYLATION
ACID HYDROLYSIS
ADENOSINE
AMINO ACIDS
ARGININE
CELL CULTURES
ELECTROPHORESIS
ENZYME INHIBITORS
HELA CELLS
HYDROLASES
METHIONINE
MOLECULAR WEIGHT
PRECURSOR
TRACER TECHNIQUES
TRITIUM COMPOUNDS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DECOMPOSITION
DRUGS
ENZYMES
HYDROLYSIS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIPOTROPIC FACTORS
LYSIS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PROTEINS
RIBOSIDES
SOLVOLYSIS
550201* - Biochemistry- Tracer Techniques