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U.S. Department of Energy
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N-methylation of calmodulin

Thesis/Dissertation ·
OSTI ID:6655572
S-adenosylmethionine: calmodulin (lysine) N-methyltransferase (CLNMT, E.C. 2.1.1.60) catalyzes the post translational conversion of lysine/sub 115/ of calmodulin to trimethyllysine in most species. Two radiometric assays for CLNMT were developed; both measured incorporation of (/sup 3/H)methyl groups from S-adenosyl-(methyl-/sup 3/H)-methionine (SAM) into non-N-methylated calmodulin isolated from Dictyostelium discoideum. One assay measured incorporation of radioactivity into acid-precipitable protein; in the other assay, (/sup 3/H)methyl calmodulin was reisolated from reaction mixtures by calcium-dependent chromatography on phenyl-Sepharose. CLNMT is cytosolic. Its levels were determined in seven tissues; in five tissues, the rank order of CLNMT content was the same as the rank order of calmodulin content. From high levels to low; testis, brain, liver, heart, and skeletal muscle. In spleen and kidney, CLMNT levels were high, similar to the levels in brain and testis, while calmodulin levels were moderate, similar to those in liver. The variation in calmodulin levels from the highest to the lowest tissue was about 11-fold, while the variation in CLNMT levels was 90-fold; tissues with the lowest calmodulin and CLNMT levels also had the lowest ratios of CLNMT to calmodulin. No additional substrates for CLNMT, other than calmodulin, were detected. Calmodulins from skeletal muscle, heart and liver were found to be incompletely methylated.
Research Organization:
Wisconsin Univ., Madison (USA)
OSTI ID:
6655572
Country of Publication:
United States
Language:
English