Identification of highly methylated arginine residues in an endogenous 20-kDa polypeptide in cancer cells

Life Sci. 1999;65(8):737-45. doi: 10.1016/s0024-3205(99)00300-8.


Enzymatic methylation of endogenous proteins in several cancer cell lines was investigated to understand a possible relationship between protein-arginine methylation and cellular proliferation. Cytosolic extracts prepared from several cancer cells (HeLa, HCT-48, A549, and HepG2) and incubated with S-adenosyl-L-[methyl-3H]methionine revealed an intensely [methyl-3H]-labeled 20-kDa polypeptide. On the other hand, cytosolic extracts prepared from normal colon cells did not show any methylation of the 20-kDa protein under identical conditions. To identify nature of the 20-kDa polypeptide, purified histones were methylated with HCT-48 cytosolic extracts and analyzed by SDS-PAGE. However, none of the histones comigrated with the methylated 20-kDa polypeptide, indicating that it is unlikely to be any of the histone subclasses. The [methyl-3H]group in the 20-kDa polypeptide was stable at pH 10-11 (37 degrees C for 30 min) and methylation was not stimulated by GTPgammaS (4 mM), thus the reaction is neither carboxyl methylesterification on isoaspartyl residues, nor on C-terminal farnesylated cysteine. The present study together with the previous identification of N(G)-methylated arginine residues in the HCT-48 cytosol fraction suggests that this novel endogenous 20-kDa arginine-methylation is a cellular proliferation-related posttranslational modification reaction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Extracts / chemistry
  • Cell Transformation, Neoplastic / chemistry
  • HeLa Cells / chemistry
  • Humans
  • Methylation
  • Neoplasm Proteins / chemistry*
  • Protein-Arginine N-Methyltransferases / analysis*
  • Tritium
  • Tumor Cells, Cultured / chemistry*
  • Tumor Cells, Cultured / cytology


  • Cell Extracts
  • Neoplasm Proteins
  • Tritium
  • Protein-Arginine N-Methyltransferases