McClure J E, Noonan C A, Shearer W T
Department of Pediatrics, Baylor College of Medicine, Houston, Texas.
Biochem Biophys Res Commun. 1993 Dec 30;197(3):1578-84. doi: 10.1006/bbrc.1993.2658.
A competition radioimmunoassay specific for conserved Domain V of p53 revealed that Domain V was masked in highly phosphorylated cytosolic p53 of resting T lymphocytes and unmasked through dephosphorylation during lymphocyte activation. Phosphatase type 2A was shown to act upon immunopurified p53 in a manner that increased the immunoreactivity of the molecule in the Domain V RIA. Treatments of T cells with okadaic acid (1nM) prior to addition of Concanavalin-A/serum inhibited completely the dephosphorylation of cytosolic p53 observed to occur within 10-20min of stimulation. Brief exposure of T cells to okadaic acid during the first hour of activation by mitogens produced increased rates of cellular proliferation. Sustained inhibition of the dephosphorylation of cytoplasmic p53 in cells undergoing mitogenic stimulation may affect adversely the ability of p53 to exert its anti-proliferative effect and could contribute to unregulated cell growth.
一种针对p53保守结构域V的竞争性放射免疫分析显示，在静息T淋巴细胞高度磷酸化的胞质p53中，结构域V被掩盖，而在淋巴细胞激活过程中通过去磷酸化而暴露。已证明2A型磷酸酶作用于免疫纯化的p53，其方式增加了该分子在结构域V放射免疫分析中的免疫反应性。在用刀豆球蛋白A/血清刺激之前，用冈田酸（1nM）处理T细胞，完全抑制了在刺激后10 - 20分钟内观察到的胞质p53的去磷酸化。在有丝分裂原激活的第一小时内，T细胞短暂暴露于冈田酸会提高细胞增殖速率。在经历有丝分裂刺激的细胞中持续抑制细胞质p53的去磷酸化可能会对p53发挥其抗增殖作用的能力产生不利影响，并可能导致细胞生长失控。
