Wadzinski B E, Heasley L E, Johnson G L
Division of Basic Sciences, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206.
J Biol Chem. 1990 Dec 15;265(35):21504-8.
Protein purification and molecular cloning have defined five classes of protein serine-threonine phosphatase catalytic subunits referred to as types 1, 2A, 2B (calcineurin), 2C, and X. Protein serine-threonine phosphatases 1, 2A, 2B, and X appear to have significant sequence homologies, whereas the 2C enzyme is more divergent. We have used the polymerase chain reaction to define the multiplicity of the closely related types 1, 2A, 2B, and X phosphatase catalytic subunits in two clonal cell lines, rat PC12 pheochromocytoma and rat FTO-2B hepatoma. RNAs for all four related phosphatase types were expressed in both cell lines. In addition to the phosphatase X enzyme, four phosphatase 1, two phosphatase 2A, and three phosphatase 2B isoforms were identified in PC12 and FTO-2B cells. The results indicate a large multiplicity of protein serine-threonine phosphatases within clonal cells of different tissue origin, suggesting that their role in cell regulation will be as divergent as that for the protein serine-threonine kinases.
蛋白质纯化和分子克隆已确定了五类蛋白质丝氨酸 - 苏氨酸磷酸酶催化亚基，分别称为1型、2A型、2B型（钙调神经磷酸酶）、2C型和X型。蛋白质丝氨酸 - 苏氨酸磷酸酶1型、2A型、2B型和X型似乎具有显著的序列同源性，而2C型酶的差异更大。我们利用聚合酶链反应确定了两种克隆细胞系（大鼠嗜铬细胞瘤PC12和大鼠肝癌FTO - 2B）中密切相关的1型、2A型、2B型和X型磷酸酶催化亚基的多样性。两种细胞系中均表达了所有四种相关磷酸酶类型的RNA。除了磷酸酶X型酶外, 在PC12和FTO - 2B细胞中还鉴定出四种磷酸酶1型、两种磷酸酶2A型和三种磷酸酶2B型同工型。结果表明，不同组织来源的克隆细胞内存在大量的蛋白质丝氨酸 - 苏氨酸磷酸酶，这表明它们在细胞调节中的作用将与蛋白质丝氨酸 - 苏氨酸激酶一样具有多样性。
