Diversity of methyl acceptor proteins in rat pheochromocytoma (PC12) cells revealed after treatment with adenosine dialdehyde.
Protein N-methylation is a widespread modification whose functions are poorly understood. To overcome the inherent technical difficulties in identification of N-methylated proteins, we cultured PC12 cells with a methylation inhibitor, in expectation that proteins would accumulate in a hypomethylated state. Cell extracts were then incubated with [methyl-3H]S-adenosyl-L-methionine to label methyl-accepting sites via endogenous methyltransferases. Using two-dimensional gel electrophoresis we detected over 50 methyl acceptors, ranging from 18 to 120 kDa. Most had isoelectric points greater than 7.0. NG,NG-Dimethylarginine and NG-monomethylarginine accounted for about 90% of the methyl-3H-amino acids recovered after acid hydrolysis and thin-layer chromatography. The production of hypomethylated proteins should prove useful, not only in the identification of new methyl acceptors, but also in the isolation and characterization of new methyltransferases.
Najbauer
J
J
School of Biological Sciences, University of California, Irvine 92717.
Aswad
D W
DW
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000310:Adrenal Gland Neoplasms / Q000378:metabolism; D000818:Animals; D003839:Deoxyadenosines; D015180:Electrophoresis, Gel, Two-Dimensional; D008745:Methylation; D008970:Molecular Weight; D009363:Neoplasm Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010673:Pheochromocytoma / Q000378:metabolism*; D051381:Rats; D012436:S-Adenosylmethionine / Q000378:metabolism; D013872:Thionucleosides / Q000494:pharmacology; D014372:Tubercidin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D003839:Deoxyadenosines; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D013872:Thionucleosides; C018258:3-deazaadenosine; C027579:periodate-oxidized adenosine; C008500:5'-methylthioadenosine; D012436:S-Adenosylmethionine; D000241:Adenosine; D014372:Tubercidin; C006235:sinefungin