A method has been developed for binding calmodulin, radioiodinated by the lactoperoxidase method, to denaturing gels and has been used to attempt to identify the calmodulin-binding proteins of cerebral cortex postsynaptic densities (PSDs). Calmodulin primarily bound to the major 51,000 Mr protein in a saturatable manner; secondarily bound to the 60,000 Mr region, 140,000 Mr region, and 230,000 ...

Constitutive isoforms of nitric oxide synthase (NOS) are activated by transient binding of Ca(2+)/Calmodulin. Here, we characterize the binding of Calmodulin to purified neuronal NOS (nNOS). [125I]Calmodulin bound to a single class of non-interacting and high affinity sites on nNOS. [125I]Calmodulin binding achieved rapid saturation, was linear with nNOS concentration, and exhibited a strict de...

Kinesin-like calmodulin-binding protein (KCBP) is a recently identified novel kinesin-like protein that appears to be unique to and ubiquitous in plants. KCBP is distinct from all other known KLPs in having a calmodulin-binding domain adjacent to its motor domain. We have used different regions of KCBP to study its interaction with tubulin subunits and the regulation of this interaction by Ca(2...

Solution x-ray scattering using synchrotron radiation as an x-ray source has been used to study the solution structure of calmodulin complexed with substance P, a undecapeptide neurotransmitter. The x-ray data indicate that the complex has a compact globular structure, the formation of which is dependent upon the binding of Ca2+ to calmodulin. In the Ca(2+)-saturated condition, the radius of gy...

The skeletal muscle calcium release channel, ryanodine receptor, is activated by calcium-free calmodulin and inhibited by calcium-bound calmodulin. Previous biochemical studies from our laboratory have shown that calcium-free calmodulin and calcium bound calmodulin protect sites at amino acids 3630 and 3637 from trypsin cleavage (Moore, C. P., Rodney, G., Zhang, J. Z., Santacruz-Toloza, L., Str...

In this study, we present data that support the presence of two distinct calmodulin binding sites within the angiotensin II receptor (AT(1A)), at juxtamembrane regions of the N-terminus of the third intracellular loop (i3, amino acids 214-231) and carboxyl tail of the receptor (ct, 302-317). We used bioluminescence resonance energy transfer assays to document interactions of calmodulin with the...

Calmodulin is an important modulator of intracellular calcium processes and may be implicated in the calcium malabsorption of coeliac disease. The calmodulin content in extracts of duodenal biopsy specimens from 48 normal control subjects and 28 patients with coeliac disease was determined. Radioimmunoassay was used to measure immunoreactive calmodulin while a cyclic adenosine 3',5'-monophospha...

Ca2+ signalling to the nucleus is thought to occur by calmodulin entry into the nucleus where calmodulin has many functions. In the present study we have investigated the role of Ca2+ and the N- and C-terminal lobes of calmodulin in its subnuclear targeting by using fluorescently labelled calmodulin and its mutants and confocal microscopy. Our data show, first, that Ca2+ stimulation induces a r...

Epilepsy is linked to mutations in KCNQ channels. KCNQ channels including KCNQ2 and KCNQ3 are enriched in neurons, regulating action potential generation and modulation. Here, we showed that properties of KCNQ2 channel in rat hippocampal cultured neurons are regulated by ubiquitous calcium sensor calmodulin. We analyzed calmodulin function on the KCNQ2 channel in both HEK293 cells and neurons. ...

Activation of CaMKII by calmodulin and the subsequent maintenance of constitutive activity through autophosphorylation at threonine residue 286 (Thr286) are thought to play a major role in synaptic plasticity. One of the effects of autophosphorylation at Thr286 is to increase the apparent affinity of CaMKII for calmodulin, a phenomenon known as "calmodulin trapping". It has previously been sugg...