Polyamines inhibit phospholipase C-catalysed polyphosphoinositide hydrolysis. Studies with permeabilized GH3 cells.
Polyamines inhibit phospholipase C-catalysed polyphosphoinositide hydrolysis. Studies with permeabilized GH3 cells.
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多胺抑制磷脂酶 C 催化的多磷酸肌醇水解。
DOI：
10.1042/bj2551015
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Fain,JN
中科院分区：
文献类型：
--
作者：
Wojcikiewicz,RJ;Fain,JN
[3 H]肌醇标记的GH 3大鼠垂体前叶肿瘤细胞用毛地黄皂苷透化，并在37 ℃下在ATP和Mg 2+存在下孵育。[3 H]聚磷酸肌醇分解和[3 H]肌醇磷酸生产的抗水解GTP类似物和Ca 2+刺激。在测试的核苷酸中，鸟苷5′-[γ-硫代]三磷酸（GTP γ S）是最有效的刺激。GTP γ S的激活似乎是由鸟嘌呤核苷酸结合（G）蛋白介导的，因为GTP γ S刺激的[3 H]磷酸肌醇的产生受到其他核苷酸的抑制，其效力顺序为GTP = GDP =鸟苷5′-[β-硫代]二磷酸大于ITP大于GMP大于UTP = CTP =腺苷5′-[γ-硫代]三磷酸。10 μ M-GTP γ S对[3 H]磷酸肌醇水平的刺激作用可被精胺和亚精胺逆转，IC 50值约为1.5%。0.25和2 mM。腐胺仅在较高浓度下具有抑制作用。类似地，GTP γ S诱导的[3 H]聚磷酸肌醇水平降低可被2.5 mM精胺逆转。超最大浓度的GTP γ S不能克服精胺的抑制作用。相比之下，通过向孵育培养基中加入0.3- 0. 6 mM-Ca 2+刺激的[3 H]肌醇磷酸产生仅被精胺（5 mM）部分抑制，并且当加入的Ca 2+增加至1 mM时精胺不具有抑制作用。这些数据表明多胺，特别是精胺，抑制磷脂酶C催化的聚磷酸肌醇水解，对GTP γ S的刺激作用具有显著的选择性。
[3H]Inositol-labelled GH3 rat anterior pituitary tumour cells were permeabilized with digitonin and were incubated at 37 degrees C in the presence of ATP and Mg2+. [3H]Polyphosphoinositide breakdown and [3H]inositol phosphate production were stimulated by hydrolysis-resistant GTP analogues and by Ca2+. Of the nucleotides tested, guanosine 5′-[gamma-thio]triphosphate (GTP gamma S) was the most effective stimulus. Activation by GTP gamma S appeared to be mediated by a guanine nucleotide-binding (G) protein as GTP gamma S-stimulated [3H]inositol phosphate production was inhibited by other nucleotides with a potency order of GTP = GDP = guanosine 5′-[beta-thio]diphosphate greater than ITP greater than GMP greater than UTP = CTP = adenosine 5′-[gamma-thio]triphosphate. The stimulatory effects of 10 microM-GTP gamma S on [3H]inositol phosphate levels were reversed by spermine and spermidine with IC50 values of approx. 0.25 and 2 mM respectively. Putrescine was inhibitory only at higher concentrations. Similarly, GTP gamma S-induced decreases in [3H]polyphosphoinositide levels were reversed by 2.5 mM-spermine. The inhibitory effects of spermine were not overcome by supramaximal concentrations of GTP gamma S. In contrast, [3H]inositol phosphate production stimulated by addition of 0.3-0.6 mM-Ca2+ to incubation media was only partially inhibited by spermine (5 mM), and spermine was not inhibitory when added Ca2+ was increased to 1 mM. These data show that polyamines, particularly spermine, inhibit phospholipase C-catalysed polyphosphoinositide hydrolysis with a marked selectivity towards the stimulatory effects of GTP gamma S.