Hippocalcin Distribution between the Cytosol and Plasma Membrane of Living Cells
| Autor: | B. Olifirov, Ye. Sheremet, P. Belan, A. Okhrimenko, Volodymyr Cherkas, O. Bagatskaya |
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| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
biology Physiology Hippocalcin Chemistry General Neuroscience Fluorescence recovery after photobleaching chemistry.chemical_element Calcium Hippocampal formation 03 medical and health sciences Cytosol 030104 developmental biology 0302 clinical medicine Membrane Membrane protein biology.protein Biophysics 030217 neurology & neurosurgery Intracellular |
| Zdroj: | Neurophysiology. 52:2-13 |
| ISSN: | 1573-9007 0090-2977 |
| DOI: | 10.1007/s11062-020-09845-6 |
| Popis: | Hippocalcin (HPCA) is a neuronal calcium sensor (NCS) protein that provides intracellular signaling via its Ca2+-dependent translocation from the cytosol to the plasma membrane. Although such translocation of HPCA and other NCS proteins is well established, no quantitative estimates of HPCA distribution between the cytosol and plasma membrane at the basal level of the intracellular free calcium concentration ([Ca2+]i) have been obtained. Thus, it is still unknown whether HPCA regulates its plasma membrane targets under resting conditions. In this work, we have evaluated this distribution in living cells at the basal level of [Ca2+]i, comparing HPCA spatial distribution with that of exogenously expressed membrane protein, EYFP-Mem. Using fluorescence recovery after photobleaching, we showed that the diffusion coefficient of fluorescently tagged HPCA in the dendrites of hippocampal neurons (~40 μm2/sec) is within the range of values typical of cytosolic proteins. The coefficient was about 10-fold higher than that for EYFP-Mem. Both results indicate that HPCA is mainly localized in the cytosol of the dendrites of hippocampal neurons. Next, direct calculations for HPCA fractions in the cytosol and plasma membrane at the basal level of [Ca2+]i demonstrated that the plasma membrane fraction of HPCA does not exceed 8%. Altogether, our results suggest that although being mainly cytosolic, HPCA may potentially signal its plasma membrane targets under resting conditions. New approaches used for obtaining such estimates can be applied for quantitative evaluation of NCS protein distribution in living cells under different experimental conditions and for the development of precise biophysical models of their signaling. |
| Databáze: | OpenAIRE |
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