Carboxyl methylation and COOH-terminal processing of the brain G-protein γ-subunit

Peter S. Backlund, William F. Simonds, Allen M. Spiegel

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38 Scopus citations


The enzymatic methylation of the guanine nucleotide-binding proteins (G-proteins) γ-subunit was investigated in brain membranes. Brain membranes were methylated in vitro using [3H-methyl]S-adenosylmethionine, and the G-protein βγ-complex was purified using an anti-β antibody to assay for the protein during purification. The isolated G-protein δγ-complex was found to be carboxyl methylated on the γ-subunit. The methyl group was localized by tryptic digestion to the carboxyl-terminal of the protein. The methylated tryptic peptides contained a modified cysteine and were very hydrophobic, suggesting additional modification by lipidation. The evidence suggests that the COOH-terminal of G-γ is modified in a manner similar to the processing that occurs with the ras proteins.

Original languageEnglish (US)
Pages (from-to)15572-15576
Number of pages5
JournalJournal of Biological Chemistry
Issue number26
StatePublished - Sep 15 1990
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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