Characterization of NAADP+ binding in sea urchin eggs
Characterization of NAADP+ binding in sea urchin eggs
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DOI：
10.1006/bbrc.2000.3444
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发表时间：
2000-09-16
影响因子：
3.1
通讯作者：
Genazzani, AA
中科院分区：
文献类型：
--
作者：
Billington, RA;Genazzani, AA
烟酸腺嘌呤二核苷酸磷酸（NAADP（+））是一种吡啶核苷酸，已被证明可以从棘皮动物、海鞘、哺乳动物和植物的细胞内膜释放Ca 2+。NAADP通过一种不依赖于ryanodine和1，4，5-三磷酸肌醇（IP 3）受体的机制释放Ca ~（2+），NAADP（+）受体可能位于一个单独的细胞器上。我们研究了海胆卵匀浆中NAADP（+）与其受体的结合特性。NAADP（+）以高亲和力（Kd = 193 +/- 35.7 pM）与可饱和的膜结合位点结合。NAADP（+）与其受体结合的t（1/2）约为7 min，而在实验过程中不发生解离。此外，NAD（+）、NAAD（+）、ADP或ATP不能取代NAADP（+）结合。结构相关分子NADP（+）和NADPH对结合位点的亲和力明显较低，Kd分别比NAADP（+）高500倍和25，000倍。氧化和还原形式的NADP（+）之间的这种差异可能表明NAADP（+）信号本身受细胞氧化还原状态的调节。(C)北京大学出版社.
Nicotinic acid adenine dinucleotide phosphate (NAADP(+)) is a pyridine nucleotide which has been shown to release Ca2+ from intracellular membranes in echinoderms, Ascidiae, mammals, and plants. NAADP releases Ca2+ via a mechanism independent of ryanodine and inositol 1,4,5-trisphosphate (IP3) receptors and the NAADP(+) receptor is likely to be located on a separate organelle. We have investigated the binding characteristics of NAADP(+) to its receptor in sea urchin egg homogenates. NAADP(+) binds to a saturable membrane-bound site with high affinity (K-d = 193 +/- 35.7 pM). NAADP(+) associates to its receptor with a t(1/2) of approximately 7 min while dissociation does not occur during the time course of the experiment. Furthermore, NAD(+), NAAD(+), ADP, or ATP cannot displace NAADP(+) binding. The structurally related molecules NADP(+) and NADPH displayed a markedly lower affinity for the binding site with K-d's 500- and 25,000-fold higher than NAADP(+), respectively. This discrepancy between oxidized and reduced forms of NADP(+) might suggest that NAADP(+) signaling is itself regulated by the redox state of the cell. (C) 2000 Academic Press.