用冈田酸和抑制剂2研究豚鼠回肠平滑肌中的蛋白质磷酸酶组成。
Protein phosphatase composition in the smooth muscle of guinea-pig ileum studied with okadaic acid and inhibitor 2.
作者信息
Takai A, Troschka M, Mieskes G, Somlyo A V
机构信息
II. Physiologisches Institut, Universität Heidelberg, Federal Republic of Germany.
出版信息
Biochem J. 1989 Sep 1;262(2):617-23. doi: 10.1042/bj2620617.
Using okadaic acid, a potent inhibitor of type 2A and type 1 protein phosphatases, and inhibitor 2, an intrinsic inhibitory factor of type 1 phosphatase, we characterized the phosphorylated myosin light-chain (PMLC) phosphatase activity in the smooth-muscle extracts of guinea-pig ileum. In the intact fibres the control activity was 254 +/- 13 nmol of Pi/min per g wet wt. (n = 15) against 32P-labelled PMLC (4 microM) from chicken gizzard. The following phosphatase fractions were identified: an inhibitor-2-sensitive (type 1) fraction (fractional activity = 35%), a Mg2+-dependent and okadaic acid-insensitive (type 2C) fraction (17%), and two type 2A-like fractions that had different susceptibility to okadaic acid. The type 2A-like fraction with lower affinity to okadaic acid accounted for 30% of the control activity. After the cell membrane was permeabilized by Triton X-100, more than 60% of this fraction remained and accounted for about 90% of the total activity, whereas the other fractions were nearly abolished. The type 2A-like fraction may be bound to some intracellular structure such as contractile proteins.
我们使用冈田酸（一种强效的2A型和1型蛋白磷酸酶抑制剂）和抑制剂2（1型磷酸酶的内在抑制因子），对豚鼠回肠平滑肌提取物中的磷酸化肌球蛋白轻链（PMLC）磷酸酶活性进行了表征。在完整纤维中，对照活性为每克湿重254±13 nmol Pi/分钟（n = 15），作用于来自鸡砂囊的32P标记的PMLC（4 μM）。鉴定出以下磷酸酶组分：抑制剂2敏感的（1型）组分（活性分数= 35%）、Mg2+依赖性且对冈田酸不敏感的（2C型）组分（17%），以及两个对冈田酸敏感性不同的2A型样组分。对冈田酸亲和力较低的2A型样组分占对照活性的30%。在用 Triton X-100使细胞膜通透后，该组分中超过60%留存下来，约占总活性的90%，而其他组分几乎被消除。2A型样组分可能与某些细胞内结构如收缩蛋白结合。
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