The variable subunit associated with protein phosphatase 2A0 defines a novel multimember family of regulatory subunits.
The variable subunit associated with protein phosphatase 2A0 defines a novel multimember family of regulatory subunits.
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与蛋白磷酸酶 2A0 相关的可变亚基定义了一个新的多成员调节亚基家族。
DOI：
10.1042/bj3170187
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
B. Hemmings
中科院分区：
文献类型：
--
作者：
S. Zołnierowicz;C. V. Hoof;N. Andjelkovic;P. Cron;I. Stevens;W. Merlevede;J. Goris;B. Hemmings
从兔骨骼肌中分离出两种蛋白磷酸酶2A（PP 2A）全酶，除了催化和PR 65调节亚基外，还含有表观分子量分别为61和56 kDa的蛋白质。这两种全酶显示低的基础磷酸化酶磷酸酶活性，这可以刺激鱼精蛋白的程度类似于以前的特点PP 2A全酶。蛋白质微测序的胰蛋白酶肽衍生自61 kDa的蛋白质，称为PR 61，产生117个氨基酸序列的残基。通过富集特定mRNA的分子克隆，然后通过逆转录-PCR和cDNA文库筛选，揭示了该蛋白存在于由至少三个基因编码的多种异构体中，其中一个基因产生几个剪接变体。将这些序列与现有数据库进行比较，确定了一个更多的人类基因，并预测了另一个基于兔cDNA衍生序列的基因，从而使编码PR 61家族成员的基因数量达到5个。来自PR 61的肽序列对应于推导的α或β亚型的氨基酸序列，表明纯化的PP 2A制剂是至少两种三聚体的混合物。相比之下，56 kDa亚基（称为PR 56）似乎对应于PR 61的α亚型。属于PR 61家族的PP 2A的几个调节亚基含有用于核定位的共有序列，因此可能将PP 2A靶向于核底物。
Two protein phosphatase 2A (PP2A) holoenzymes were isolated from rabbit skeletal muscle containing, in addition to the catalytic and PR65 regulatory subunits, proteins of apparent molecular masses of 61 and 56 kDa respectively. Both holoenzymes displayed low basal phosphorylase phosphatase activity, which could be stimulated by protamine to an extent similar to that of previously characterized PP2A holoenzymes. Protein micro-sequencing of tryptic peptides derived from the 61 kDa protein, termed PR61, yielded 117 residues of amino acid sequence. Molecular cloning by enrichment of specific mRNAs, followed by reverse transcription-PCR and cDNA library screening, revealed that this protein exists in multiple isoforms encoded by at least three genes, one of which gives rise to several splicing variants. Comparisons of these sequences with the available databases identified one more human gene and predicted another based on a rabbit cDNA-derived sequence, thus bringing the number of genes encoding PR61 family members to five. Peptide sequences derived from PR61 corresponded to the deduced amino acid sequences of either alpha or beta isoforms, indicating that the purified PP2A preparation was a mixture of at least two trimers. In contrast, the 56 kDa subunit (termed PR56) seems to correspond to the epsilon isoform of PR61. Several regulatory subunits of PP2A belonging to the PR61 family contain consensus sequences for nuclear localization and might therefore target PP2A to nuclear substrates.