RANGE OF MESSENGER ACTION OF CALCIUM-ION AND INOSITOL 1,4,5-TRISPHOSPHATE
RANGE OF MESSENGER ACTION OF CALCIUM-ION AND INOSITOL 1,4,5-TRISPHOSPHATE
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DOI：
10.1126/science.1465619
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发表时间：
1992-12-11
期刊：
影响因子：
56.9
通讯作者：
STRYER, L
中科院分区：
文献类型：
--
作者：
ALLBRITTON, NL;MEYER, T;STRYER, L
通过测定点源钙离子或肌醇1，4，5-三磷酸(IP3)在非洲爪哇卵母细胞胞液中的扩散系数，确定了它们的信使作用范围。[H-3]IP3在萃取物中的扩散系数(D)为283mm2/S，当游离钙浓度从90 nM增加到1um时，[H-3]IP3对钙离子的扩散系数从13增加到65mm2/S。Ca~(2+)在生理浓度范围内的缓慢扩散是由于它与缓慢流动或静止的缓冲液结合所致。由扩散系数和寿命推算出缓冲前、缓冲前和IP3的有效范围分别为0.1um、5um和24um。因此，对于小于20微米的细胞中的瞬时信使点源，IP3是一个全局信使，而钙离子则作用于有限的区域。
The range of messenger action of a point source of Ca2+ or inositol 1,4,5-trisphosphate (IP3) was determined from measurements of their diffusion coefficients in a cytosolic extract from Xenopus laevis oocytes. The diffusion coefficient (D) of [H-3]IP3 injected into an extract was 283 mum2/s. D for Ca2+ increased from 13 to 65 mum2/s when the free calcium concentration was raised from about 90 nM to 1 muM. The slow diffusion of Ca2+ in the physiologic concentration range results from its binding to slowly mobile or immobile buffers. The calculated effective ranges of free Ca2+ before it is buffered, buffered Ca2+, and IP3 determined from their diffusion coefficients and lifetimes were 0.1 mum, 5 mum, and 24 mum, respectively. Thus, for a transient point source of messenger in cells smaller than 20 mum, IP3 is a global messenger, whereas Ca2+ acts in restricted domains.