IN-VIVO AND IN-VITRO BINDING OF MICROCYSTIN TO PROTEIN PHOSPHATASE-1 AND PHOSPHATASE-2A
IN-VIVO AND IN-VITRO BINDING OF MICROCYSTIN TO PROTEIN PHOSPHATASE-1 AND PHOSPHATASE-2A
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DOI：
10.1006/bbrc.1995.2605
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发表时间：
1995-11-02
影响因子：
3.1
通讯作者：
ZHANG, LF
中科院分区：
文献类型：
--
作者：
RUNNEGAR, M;BERNDT, N;ZHANG, LF
肝毒性微囊藻毒素(Mcyst)是丝氨酸/苏氨酸蛋白磷酸酶(PP1和PP2A)的有效抑制剂，其IC50‘S为0.1-1.0 nM。Mcyst和其他PP抑制剂，如冈田酸或Calyculin A，与PP1和PP2A的C末端区域相互作用。利用[I-125]-Mcyst和针对PP1和PP2A的抗体，我们通过免疫沉淀和放射自显影证明，在肝细胞中，Mcyst与PP1和PP2A催化亚基形成第二次共价键。我们证明了Mcyst的甲基脱氢丙氨酸残基的亲电性α，β不饱和羰基与位于PPI C-末端的Cys 273的硫醇(PP2A中的Cys 266)反应所产生的键，因为PP1α中Cys 273到Ala的定点突变导致完全丧失形成共价Mcyst-PP1加合物的能力。(C)1995年学术出版社。
The hepatotoxic microcystins (Mcyst) are potent inhibitors of the ser/thr protein phosphatases (PP1 and PP2A) with IC50's of 0.1-1.0 nM. Mcyst and other PP inhibitors like okadaic acid or calyculin A interact with the C-terminal region of PP1 and PP2A. Using [I-125]-Mcyst and antibodies specific for PP1 and PP2A, we show by immunoprecipitation and autoradiography, that in hepatocytes Mcyst forms secondary covalent bonds with both PP1 and PP2A catalytic subunits. We demonstrate that the bond resulted from the reaction between the electrophilic alpha,beta unsaturated carbonyl of the methyldehydroalanine residue of Mcyst and the thiol of Cys 273 located in the C-terminal of PPI (Cys 266 in PP2A), since site-directed mutagenesis of Cys 273 to Ala in PP1 alpha led to complete loss of ability for the formation of a covalent Mcyst-PP1 adduct. (C) 1995 Academic Press, Inc.