- 作者: Ming-Ling Chen; Yong-Cyuan Chen; I-Wei Peng; Ruo-Lin Kang; Meng-Pei Wu; Po-Wen Cheng; Po-Yuan Shih; Li-Long Lu; Chih-Cheng Yang; Chien-Yuan Pan
- 作者服務機構: 1 Institute of Zoology, National Taiwan University, Rm730, Life Science Building, 1 Roosevelt Rd., Sec. 4, Taipei, 106, Taiwan, R.O.C; ; 2 Department of Life Science, National Taiwan University, Taipei, Taiwan, R.O.C
- 中文摘要: --
- 英文摘要: Calcium binding protein-1 (CaBP1) is a calmodulin like protein shown to modulate Ca2+ channel activities. Here, we explored the functions of long and short spliced CaBPl variants (L- and S-CaBP1) in modulating stimulus-secretion coupling in primary cultured bovine chromaffin cells. L- and S-CaBP1 were cloned from rat brain and fused with yellow fluorescent protein at the C-terminal. When expressed in chromaffin cells, wild-type L- and S-CaBPls could be found in the cytosol, plasma membrane and a perinuclear region; in contrast, the myristoylation-deficient mutants were not found in the membrane. More than 20 and 70% of Na+ and Ca2+ currents, respectively, were inhibited by wild-type isoforms but not myristoylation-deficient mutants. The [Ca2+]i response evoked by high K+ buffer and the exocytosis elicited by membrane depolarizations were inhibited only by wild-type isoforms. Neuronal Ca2+ sensor-1 and CaBP5, both are calmodulin-like proteins, did not affect Na+,Ca2+ currents, and exocytosis. When expressed in cultured cortical neurons, the [Ca2+]i responses elicited by high-K+ depolarization were inhibited by CaBP1 isoforms. In HEK293T cells cotransfected with N-type Ca2+ channel and L-CaBP1, the current was reduced and activation curve was shifted positively. These results demonstrate the importance of CaBP1s in modulating the stimulus-secretion coupling in excitable cells.
- 中文關鍵字: --
- 英文關鍵字: calcium binding proteins, Ca2+ currents, chromaffin cells, exocytosis, neuronal calcium sensor-1, N-type Ca2+ channel