Restricted diffusion of calretinin in cerebellar granule cell dendrites implies Ca²⁺-dependent interactions via its EF-hand 5 domain
- Arendt, Oliver Carl-Ludwig Institute for Physiology, Medical Faculty, University of Leipzig, Germany
- Schwaller, Beat Unit of Anatomy, Department of Medicine, University of Fribourg, Switzerland
- Brown, Edward B. School of Medicine and Dentistry, Department of Biomedical Engineering, University of Rochester, New York
- Eilers, Jens Carl-Ludwig Institute for Physiology, Medical Faculty, University of Leipzig, Germany
- Schmidt, Hartmut Carl-Ludwig Institute for Physiology, Medical Faculty, University of Leipzig, Germany
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2013
Published in:
- The Journal of Physiology. - 2013, p. –
English
Ca²⁺-binding proteins (CaBPs) are important regulators of neuronal Ca²⁺ signaling, acting either as buffers that shape Ca²⁺ transients and Ca²⁺ diffusion and/or as Ca²⁺ sensors. The diffusional mobility represents a crucial functional parameter of CaBPs, describing their range-of-action and possible interactions with binding partners. Calretinin (CR) is a CaBP widely expressed in the nervous system with strong expression in cerebellar granule cells. It is involved in regulating excitability and synaptic transmission of granule cells, and its absence leads to impaired motor control. We quantified the diffusional mobility of dye-labelled CR in mouse granule cells using two-photon fluorescence recovery after photobleaching (FRAP). We found that movement of macromolecules in granule cell dendrites was not well described by free Brownian diffusion and that CR diffused unexpectedly slow compared to fluorescein dextrans of comparable size. During bursts of action potentials, which were associated with dendritic Ca²⁺ transients, the mobility of CR was further reduced. Diffusion was significantly accelerated by a peptide embracing EF-hand 5 of CR. Our results suggest long-lasting, Ca²⁺-dependent interactions of CR with large and/or immobile binding partners. These interactions render CR a poorly mobile Ca²⁺ buffer and point towards a Ca²⁺ sensor function of CR.
- Faculty
- Faculté des sciences et de médecine
- Department
- Département de Médecine
- Language
-
- English
- Classification
- Biological sciences
- License
- License undefined
- Identifiers
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- RERO DOC 32508
- DOI 10.1113/jphysiol.2013.256628
- Persistent URL
- https://folia.unifr.ch/unifr/documents/303047
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