Calmodulin structure refined at 1.7 Å resolution

Chattopadhyaya, Rajagopal; Meador, William E.; Means, Anthony R.; Quiocho, Florante A.

doi:10.1016/0022-2836(92)90324-d

Cited by 688 publications

(787 citation statements)

References 20 publications

Supporting

Mentioning

738

Contrasting

Order By: Relevance

“…This is important because the gCaM we cloned differs in amino acid composition from CaM purified from giardial extracts by Munoz et al (22). The amino acid composition determined by Munoz et al (22) for bovine CaM also differed from the published bovine CaM sequence (28). We cannot explain these differences, but we have confirmed our sequence, and gCaM expressed in Escherichia coli was active in stimulating cAMP phosphodiesterase activity (data not shown).…”

Section: Resultssupporting

confidence: 71%

Calcium Signaling in Excystation of the Early Diverging Eukaryote, Giardia lamblia

Reiner

Hetsko

Meszaros

et al. 2003

Journal of Biological Chemistry

View full text Add to dashboard Cite

Excystation of Giardia lamblia, which initiates infection, is a poorly understood but dramatic differentiation induced by physiological signals from the host. Our data implicate a central role for calcium homeostasis in excystation. Agents that alter cytosolic Ca 2؉ levels (1,2-bis(2-aminophenoxy)ethane-N,N,N ,N -tetraacetic acidtetra(acetyloxymethyl) ester, a Ca 2؉ channel blocker, Ca 2؉ ionophores, and thapsigargin) strongly inhibit excystation. Treatment of Giardia with thapsigargin raised intracellular Ca 2؉ levels, and peak Ca 2؉ responses increased with each stage of excystation, consistent with the kinetics of inhibition. Fluorescent thapsigargin localized to a likely Ca 2؉ storage compartment in cysts. The ability to sequester ions in membranebounded compartments is a hallmark of the eukaryotic cell. These studies support the existence of a giardial thapsigargin-sensitive Ca 2؉ storage compartment resembling the sarcoplasmic/endoplasmic reticulum calcium ATPase pump-leak system and suggest that it is important in regulation of differentiation and appeared early in the evolution of eukaryotic cells. Calmodulin antagonists also blocked excystation. The divergent giardial calmodulin localized to the eight flagellar basal bodies/centrosomes, like protein kinase A. Inhibitor kinetics suggest that protein kinase A signaling triggers excystation, whereas calcium signaling is mainly required later, for parasite activation and emergence.

show abstract

Section: Resultssupporting

confidence: 71%

Calcium Signaling in Excystation of the Early Diverging Eukaryote, Giardia lamblia

Reiner

Hetsko

Meszaros

et al. 2003

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…Calmodulin is a ubiquitously expressed Ca 2þ -binding protein that can bind four Ca 2þ ions through its four EF-hand domains (Chattopadhyaya et al 1992). This protein has been highly conserved throughout evolution, is found in all eukaryotes, and is 100% identical across all vertebrates at the amino acid level.…”

Section: Neuronal Functions Of Calmodulinmentioning

confidence: 99%

The Diversity of Calcium Sensor Proteins in the Regulation of Neuronal Function

McCue

Haynes²,

Burgoyne

2010

Cold Spring Harbor Perspectives in Biology

View full text Add to dashboard Cite

“…23 In the "double native" Gō potential used, both the apo (Ca 2+ -free) 24 and holo (Ca 2+ -bound) 25 structures are stabilized, so that occasional spontaneous transitions are observed between the two states.…”

Section: Calmodulinmentioning

confidence: 99%

On the Structural Convergence of Biomolecular Simulations by Determination of the Effective Sample Size

2007

View full text Add to dashboard Cite

Although atomistic simulations of proteins and other biological systems are approaching microsecond timescales, the quality of simulation trajectories has remained difficult to assess. Such assessment is critical not only for establishing the relevance of any individual simulation, but also in the extremely active field of developing computational methods. Here we map the trajectory assessment problem onto a simple statistical calculation of the "effective sample size" -i.e., the number of statistically independent configurations. The mapping is achieved by asking the question, "How much time must elapse between snapshots included in a sample for that sample to exhibit the statistical properties expected for independent and identically distributed configurations?" Our method is more general than standard autocorrelation methods, in that it directly probes the configuration space distribution, without requiring a priori definition of configurational substates, and without any fitting parameters. We show that the method is equally and directly applicable to toy models, peptides, and a 72-residue protein model. Variants of our approach can readily be applied to a wide range of physical and chemical systems.What does convergence mean? The answer is not simply of abstract interest, since many aspects of the biomolecular simulation field depend on it. When parameterizing potential functions, it is essential to know whether inaccuracies are attributable to the potential, rather than undersampling. 1 In the extremely active area of methods development for equilibrium sampling, it is necessary to demonstrate that a novel approach is better than its predecessors, in the sense that it equilibrates the relative populations of different conformers in less CPU time. 2 And in the important area of free energy calculations, under-sampling can result in both systematic error and poor precision. 3To rephrase the basic question, given a simulation trajectory (an ordered set of correlated configurations), what characteristics should be observed if convergence has been achieved? The obvious, if tautological, answer is that all states should have been visited with the correct relative probabilities, as governed by a Boltzmann factor (implicitly, free energy) in most cases of physical interest. Yet given the omnipresence of statistical error, it has long been accepted that such idealizations are of limited value. The more pertinent questions have therefore been taken to be: Does the trajectory give reliable estimates for quantities of interest? What is the statistical uncertainty in these estimates 4-7 ? In other words, convergence is relative, and in principle, it is rarely meaningful to describe a simulation as not converged, in an absolute sense. (An exception is when a priori information indicates the trajectory has failed to visit certain states.)

show abstract

Calmodulin structure refined at 1.7 Å resolution

Cited by 688 publications

References 20 publications

Calcium Signaling in Excystation of the Early Diverging Eukaryote, Giardia lamblia

Calcium Signaling in Excystation of the Early Diverging Eukaryote, Giardia lamblia

The Diversity of Calcium Sensor Proteins in the Regulation of Neuronal Function

On the Structural Convergence of Biomolecular Simulations by Determination of the Effective Sample Size

Contact Info

Product

Resources

About