This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Oh, S.-H. Articles by Roberts, D. M. Search for Related Content PubMed PubMed Citation Articles by Oh, S.-H. Articles by Roberts, D. M. Agricola Articles by Oh, S.-H. Articles by Roberts, D. M.

Metabolism and Enzymology

Analysis of the State of Posttranslational Calmodulin Methylation in Developing Pea Plants ¹

Department of Biochemistry, University of Tennessee, Knoxville, Tennessee 37996-0840

A specific calmodulin-N-methyltransferase was used in a radiometric assay to analyze the degree of methylation of lysine-115 in pea (Pisum sativum) plants. Calmodulin was isolated from dissected segments of developing roots of young etiolated and green pea plants and was tested for its ability to be methylated by incubation with the calmodulin methyltransferase in the presence of [³H]methyl-S-adenosylmethionine. By this approach, the presence of unmethylated calmodulins were demonstrated in pea tissues, and the levels of methylation varied depending on the developmental state of the tissue tested. Calmodulin methylation levels were lower in apical root segments of both etiolated and green plants, and in the young lateral roots compared with the mature, differentiated root tissues. The incorporation of methyl groups into these calmodulin samples appears to be specific for position 115 since site-directed mutants of calmodulin with substitutions at this position competitively inhibited methyl group incorporation. The present findings, combined with previous data showing differences in the ability of methylated and unmethylated calmodulins to activate pea NAD kinase (DM Roberts et al. [1986] J Biol Chem 261: 1491-1494) raise the possibility that posttranslational methylation of calmodulin could be another mechanism for regulating calmodulin activity.