Diversity in the regulatory B-subunits of protein phosphatase 2A: identification of a novel isoform highly expressed in brain.
Diversity in the regulatory B-subunits of protein phosphatase 2A: identification of a novel isoform highly expressed in brain.
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DOI：
10.1021/bi00205a023
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发表时间：
1994-10
期刊：
影响因子：
2.9
通讯作者：
S. Zołnierowicz;C. Csortos;J. Bondor;A. Verin;M. Mumby;A. DePaoli-Roach
中科院分区：
文献类型：
--
作者：
S. Zołnierowicz;C. Csortos;J. Bondor;A. Verin;M. Mumby;A. DePaoli-Roach
2A型蛋白磷酸酶（PP 2A）的生理作用依赖于催化亚基与多种调节亚基的缔合。为了了解PP 2A的功能，我们进行了纯化的全酶和分子克隆的调节亚基。从兔骨骼肌中纯化了两种含有不同B亚基的三聚体形式，PP 2A 0和PP 2A 1。与PP 2A 0和PP 2A 1相关的B亚基在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳上迁移，迁移率略有不同，分别为约52.5和约51.5 kDa，并显示出不同的免疫学特性。与PP 2A 0相关的B亚基的B'形式被抗牛心脏PP 2A中存在的B亚基的抗体识别，但不被兔PP 2A 1的B亚基同种型特异性抗体识别。克隆编码PP 2 A1的B亚基的cDNA导致分离出与B α亚基同种型高度同源但不同的cDNA。这种新的同种型的推导的氨基酸序列被命名为B γ，编码的蛋白质分别与B α和B β同种型有81%和87%的同一性。北方印迹分析表明，B γ同种型在兔脑中高度表达为3.9 kb的转录物。通过Western印迹分析B亚基表达表明与信息水平大致平行。总之，我们的数据揭示了PP 2A三聚体全酶的更大的复杂性，这是由于鉴定了PP 2A 1的新的B调节亚基同种型和与PP 2A 0相关的独特的B'亚基。
The physiological role of type 2A protein phosphatases (PP2A) is dependent upon the association of the catalytic subunit with a variety of regulatory subunits. In order to understand the function of PP2A, we have undertaken purification of the holoenzymes and molecular cloning of the regulatory subunits. Two trimeric forms containing distinct B-subunits, PP2A0 and PP2A1, have been purified from rabbit skeletal muscle. The B-subunits associated with PP2A0 and PP2A1 migrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with slightly different mobility, approximately 52.5 and approximately 51.5 kDa, respectively and showed distinct immunological properties. The B' form of B-subunit associated with PP2A0 was recognized by antibodies against the B-subunit present in bovine heart PP2A but not by antibodies specific to the B subunit isoforms of rabbit PP2A1. Cloning of cDNAs encoding the B subunit of PP2A1 resulted in the isolation of a cDNA highly homologous to, but distinct from, the B alpha subunit isoform. The deduced amino acid sequence of this novel isoform, which was designated B gamma, encoded a protein which was 81% and 87% identical to the B alpha and B beta isoforms, respectively. Northern blot analysis indicated that the B gamma isoform is highly expressed in rabbit brain as a transcript of 3.9 kb. Analysis of B-subunit expression by Western blot indicated a general parallel with the message levels. In conclusion, our data reveal even greater complexity of PP2A trimeric holoenzymes due to the identification of a novel B regulatory subunit isoform of PP2A1 and a distinct B' subunit associated with PP2A0.