Amano I, Ishikawa Y, Ishida H
Department of Pharmacology, Tokushima University School of Dentistry, Japan.
Res Exp Med (Berl). 1994;194(3):185-96. doi: 10.1007/BF02576379.
Protein phosphatase that removed [32P]phosphate from non-histone proteins, i.e., phenol-soluble acidic proteins, more rapidly and strongly than from histone proteins was present in nuclei of rat submandibular glands, but was not associated with chromatin. Cyclic AMP (10(-4)-10(-2) mM) stimulated the dephosphorylation of non-histone proteins, but not that of histone proteins. After a single injection of isoproterenol (IPR), the dephosphorylation of non-histone proteins in rat submandibular gland nuclei increased within 15 min, reached a maximum in 30 min and returned to normal control levels within 4 h. The stimulation of dephosphorylation of non-histone proteins induced by IPR was not observed after prior treatment of the animals with dichloroisoproterenol. The dephosphorylation of histone proteins was not affected by the injection of IPR. Stimulation of beta-adrenoceptors with IPR in rat submandibular glands resulted in increase in cyclic AMP and decrease in RNA synthesis in the tissues in the first few hours after the injection. This decrease in RNA synthesis was temporary and was preceded by the increase in cyclic AMP level and in the dephosphorylation of non-histone acidic proteins in the tissues. These results suggest that protein phosphatase in nuclei plays an important part in the events controlling RNA synthesis by regulating the state of phosphorylation of non-histone acidic proteins. In addition, the phosphatase may be regulated by a function of the cytoplasmic membranes.
大鼠下颌下腺细胞核中存在一种蛋白磷酸酶，该酶从非组蛋白（即酚溶性酸性蛋白）上去除[32P]磷酸根的速度比从组蛋白上更快、更强，且与染色质无关。环磷酸腺苷（10^(-4)-10^(-2) mM）可刺激非组蛋白的去磷酸化，但不影响组蛋白的去磷酸化。单次注射异丙肾上腺素（IPR）后，大鼠下颌下腺细胞核中非组蛋白的去磷酸化在15分钟内增加，30分钟时达到最大值，并在4小时内恢复到正常对照水平。在用二氯异丙肾上腺素预先处理动物后，未观察到IPR诱导的非组蛋白去磷酸化刺激作用。注射IPR对组蛋白的去磷酸化没有影响。在大鼠下颌下腺中用IPR刺激β-肾上腺素能受体，导致注射后的最初几个小时内组织中环磷酸腺苷增加，RNA合成减少。RNA合成的这种减少是暂时的，且在组织中环磷酸腺苷水平升高和非组蛋白酸性蛋白去磷酸化之前出现。这些结果表明，细胞核中的蛋白磷酸酶通过调节非组蛋白酸性蛋白的磷酸化状态，在控制RNA合成的事件中起重要作用。此外，该磷酸酶可能受细胞质膜功能的调节。
