| Summary: | 碩士 === 國立臺灣大學 === 動物學研究研究所 === 94 === Calmodulin is a calcium binding protein ubiquitously expressed in cells and modulates many physiological activities. Recently, a new family of calcium binding proteins was found to have similar structure to calmodulin. In this report, the functions of a member of this family, calcium binding protein-1 (CaBP1), in modulating the stimulus-secretion coupling in excitable cells was characterized. Alternative splicing L- and S-CaBP1 were cloned from rat E14.5 embryonic cortical neurons. When expressed in primary cultured bovine chromaffin and embryonic neurons, both L- and S-CaBP1-EYFP fusion proteins were found to be localized on the plasma membrane but the G2A mutants, deficient in myristoylation, was in cytosol. The changes in calcium currents and capacitance evoked by membrane depolarization were inhibited by the expression of wild type L- and S-CaBP1 but not G2A mutants. The Ca2+ imaging recorded form cells stimulated by high K+ buffer also showed comparable results. These suggest that overexpression of CaBP1s in chromaffin cells and neurons inhibit calcium currents and exocytosis. These suggest the importance of CaBP1 in modulating the stimulus-secretion coupling in excitable cells.
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