The distribution, properties, and substrate specificity of S-adenosylmethionine:calmodulin (lysine) N-methyltransferse (EC 2.1.1.60, calmodulin N-methyltransferase) of the rat have been studied. This enzyme is cytosolic and is found at high levels in tissues with high levels of calmodulin and at low levels in tissues with little calmodulin. In liver, heart, and skeletal muscle, which have low l...

Calmodulin was purified to apparent homogeneity from sea urchin spermatozoa by heat-treatment at 85 degrees C, ammonium sulphate precipitation at pH 4.2, DEAE-Sephacel chromatography and gel filtration on Sephadex G-100. Approximately 8.3 micrograms calmodulin were recovered per 10(10) sperm cells. The sperm calmodulin had an apparent molecular weight of 17 800. The purified calmodulin activate...

Calmodulin was localized in Saccharomyces cerevisiae by indirect immunofluorescence using affinity-purified polyclonal antibodies. Calmodulin displays an asymmetric distribution that changes during the cell cycle. In unbudded cells, calmodulin concentrates at the presumptive site of bud formation approximately 10 min before bud emergence. In small budded cells, calmodulin accumulates throughout...

Because human erythrocyte membrane Ca2+-ATPase is a calmodulin-dependent enzyme, and because physiological levels of thyroid hormone stimulate this enzyme system in vitro, we have studied the role of calmodulin in this model of extranuclear thyroid hormone action. Ca2+-ATPase activity in the absence of thyroid hormone ("basal activity") was increased by inclusion in the preassay incubation mixt...

Indirect immunofluorescence was used to determine the distribution of calmodulin in the mitotic apparatus of rat kangaroo PtK2 and Chinese hamster ovary (CHO) cells. The distribution of calmodulin in PtK2 cells was compared to the distribution of tubulin, also as revealed by indirect immunofluorescence. During mitosis, calmodulin was found to be a dynamic component of the mitotic apparatus. Cal...

Calmodulin regulates multifarious cellular processes via a panoply of target interactions. However, the central role, multiple isoforms, and complex target interactions of calmodulin make it difficult to examine its precise functions. Here, we analyzed calmodulin function in neurons using lentivirally delivered short-hairpin RNAs that suppressed expression of all calmodulin isoforms by approxim...

Activation of Ras induces a variety of cellular responses depending on the specific effector activated and the intensity and amplitude of this activation. We have previously shown that calmodulin is an essential molecule in the down-regulation of the Ras/Raf/MEK/extracellularly regulated kinase (ERK) pathway in cultured fibroblasts and that this is due at least in part to an inhibitory effect o...

Calmodulin was isolated and purified to homogeneity from dog pancreas. Highly purified subcellular fractions were prepared from dog pancreas by zonal sucrose-density ultracentrifugation and assayed for their ability to bind 125I-calmodulin in vitro. Proteins contained in these fractions were also examined for binding of 125I-calmodulin after their separation by polyacrylamide-gel electrophoresi...

We report a quantitative subcellular localization study of calmodulin and the subcellular distribution of calmodulin-binding proteins in normal and virus-transformed chicken embryo fibroblasts. We developed homogenization conditions for fibroblasts which give maximal cell disruption with minimal organelle destruction, prepared and characterized subcellular fractions, and measured the levels and...

Calmodulin is the predominant intracellular receptor for Ca(2+) signals, mediating the regulation of numerous cellular processes. Previous studies have shown that calcium-loaded calmodulin can bind to and inhibit the activity of certain basic helix-loop-helix (bHLH) transcription factors. The basic sequence within the bHLH domain is the primary target for calmodulin binding, and sequences modul...