ABERRANT CGMP-BINDING ACTIVITY IN NON-CHEMOTACTIC DICTYOSTELIUM-DISCOIDEUM MUTANTS
ABERRANT CGMP-BINDING ACTIVITY IN NON-CHEMOTACTIC DICTYOSTELIUM-DISCOIDEUM MUTANTS
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DOI：
10.1016/0167-4889(95)00082-4
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发表时间：
1995-08-31
影响因子：
5.1
通讯作者：
VANHAASTERT, PJM
中科院分区：
文献类型：
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作者：
KUWAYAMA, H;VIEL, GT;VANHAASTERT, PJM
在10个非趋化性突变体（KI突变体; KI-1类似于10）中研究了cGMP结合动力学与网骨藻中主要cGMP结合活性的关系。野生型细胞含有约3000个结合位点，Kd为1.5 nM。cGMP可以以快速（F型）或缓慢（S型）动力学从这些结合位点解离，并且DNA已显示促进F型cGMP结合转化为S型cGMP结合。根据平衡和非平衡结合性质以及DNA的作用，将10种突变体分为4类。I类突变体（KI-I、3和8）具有正常的cGMP结合特性。II类突变体（KI-2、6和7）显示K-d值增加，但B-max、F/S比和DNA效应接近正常。III类突变体（KI-4、5和10）具有强烈降低的K-d和增加的B-max，几乎所有结合位点都是S型的，并且DNA不影响结合;显然这些突变体具有锁定在S型的cGMP结合蛋白。IV类突变体（KI-9）中cGMP结合是正常的，除了结合位点的数量增加约S倍。在10个非趋化突变体中发现7个突变体与cGMP结合发生改变，表明cGMP结合活性在趋化信号转导途径中起重要作用。
The kinetics of cGMP-binding to the major cGMP-binding activity in Dictyostelium, were investigated in 10 non-chemotactic mutants (KI mutants; KI-1 similar to 10). A wild-type cell contains about 3000 binding sites with a K-d of 1.5 nM. cGMP may dissociate from these binding sites with fast (F-type) or slow (S-type) kinetics, and DNA has been shown to promote the conversion of F- to S-type of cGMP-binding. The 10 mutants were placed in 4 classes, based on equilibrium and non-equilibrium binding properties and the effect of DNA. Class I mutants (KI-I, 3 and 8) have normal cGMP-binding properties. Class II mutants (KI-2, 6 and 7) show increased K-d values but nearly normal B-max, normal F/S ratio and normal effects of DNA. Class III mutants (KI-4, 5 and 10) have a strongly decreased K-d and increased B-max, nearly all binding sites are of the S-type and DNA does not affect the binding; apparently these mutants have a cGMP-binding protein locked in the S-form. cGMP-binding in class IV mutant (KI-9) is normal except that the number of binding sites is increased about S-fold. The finding of seven mutants with altered cGMP-binding in 10 non-chemotactic mutants suggests that the cGMP-binding activity plays an important role in the chemotactic signal transduction pathway.