A novel Ca2+‐dependent step in exocytosis subsequent to vesicle fusion

FEBS Letters

Lindau, Manfred¹  Hartmann, Jana¹ 

[1] Abt. Molekulare Zellforschung, Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, D-69120 Heidelberg, Germany

关键词: Exocytosis;    Calcium;    Eosinophil;    Fusion pore;    EGTA;    ethylene glycol-bis(β-amino-ethyl ether)-N;    N;    N′;    N′-tetraacetic acid;    HEDTA;    N-hydroxyethylethylenediaminetriacetic acid;    GTPγS;    guanosine-5′-O-(3-thiotriphosphate);   

DOI  :  10.1016/0014-5793(95)00318-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Exocytosis begins with formation of a small fusion pore which then expands allowing rapid release of granular contents. We studied the influence of cytoplasmic free Ca²⁺ ([Ca²⁺]_i) on the conductance of the initial pore and on the dynamics of subsequent expansion in horse eosinophils using the patch clamp technique. The mean initial conductance is ∼200 pS independent of [Ca²⁺]_i. This value is close to that previously found in beige mouse mast cells. The pore subsequently expands by 18 nS/s at [Ca²⁺]_i < 10 nM, by 40 nS/s at [Ca²⁺]_i = 1.5 μM and by 90 nS/s at [Ca²⁺]_i = 10 μM. These results show that the structure of the initial fusion pore is independent of cytoplasmic Ca²⁺. However, the pore expansion is a Ca²⁺-dependent process modulating secretion at a step later than vesicle-plasma membrane fusion.

【 授权许可】

Unknown