Biophysical investigation of retinal calcium sensor function.
BACKGROUND
Neuronal calcium sensor proteins represent a subgroup of the family of EF-hand calcium binding proteins. Members of this subgroup are the guanylate cyclase-activating proteins and recoverin, which operate as important calcium sensors in retinal photoreceptor cells. Physiological and biochemical data indicate that these proteins participate in shaping the photoreceptor light response.


METHODS
Biophysical methods have been widely applied to investigate the molecular properties of retinal calcium binding proteins like the guanylate cyclase-activating proteins and recoverin. Properties include the determination of calcium affinities by isotope techniques and spectroscopical approaches. Conformational changes are investigated for example by tryptophan fluorescence emission. A special focus of this review is laid on a new experimental approach to study conformational changes in calcium binding proteins by surface plasmon resonance spectroscopy. In addition this technique has been employed for measuring the calcium-dependent binding of calcium sensors to membranes.


CONCLUSIONS
Biophysical approaches provide valuable information about key properties of calcium sensor proteins involved in intracellular signalling. Parameters of their molecular properties like calcium binding and conformational changes help to define their physiological role derived from cellular, genetic or physiological studies.


CONCLUSIONS
Calcium is an important second messenger in intracellular signaling. Calcium signals are propagated via calcium binding proteins that are able to discriminate between incremental differences in intracellular calcium and that regulate their targets with high precision and specificity. This article is part of a Special Issue entitled Biochemical, biophysical and genetic approaches to intracellular calcium signalling.
Biochemistry Group, Institute of Biology and Environmental Science, Faculty V, Carl von Ossietzky University Oldenburg, Oldenburg, Germany. karl.w.koch@uni-oldenburg.de
Karl-Wilhelm
KW
Koch
D000818:Animals; D002118:Calcium / Q000737:chemistry*; D002135:Calcium-Binding Proteins / Q000737:chemistry*; D002942:Circular Dichroism; D005136:Eye Proteins / Q000737:chemistry*; D006801:Humans; D055767:Immobilized Proteins / Q000737:chemistry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D020349:Surface Plasmon Resonance
D002135:Calcium-Binding Proteins; D005136:Eye Proteins; D055767:Immobilized Proteins; D002118:Calcium