吲哚丁酸通过蛋白磷酸化激活湖北海棠根系Ca2+-ATP酶

以湖北海棠(Malus hupehensis Rhed.)实生苗为试材,通过在砂培液中加入吲哚丁酸(IBA)和蛋白激酶抑制剂3,3’,4’,5,7-五羟黄酮(quercetin)研究了IBA对根系膜蛋白磷酸化和Ca2 -ATPase活性的影响.试验表明根系膜蛋白磷酸化反应主要发生在丝氨酸残基上100 μmol/L的IBA使蛋白激酶和Ca2 -ATPase活性在2～3h内升高数十倍,之后很快下降,蛋白激酶活性变化明显早于Ca2 -ATPase;蛋白激酶抑制剂quercetin不仅抑制根系膜蛋白的磷酸化,也显著削弱IBA对Ca2 -ATPase的激活作用.结果显示,在对IBA响应中Caa2 -ATPase是信号转导途径中的成员,IBA可能通过蛋白磷酸化激活根系Ca2 -ATPase而起作用.

Indole Butyric Acid Activates Ca2+-ATPase in Malus hupehensis Rhed.Roots by Protein Phosphorylation

The effect of IBA on protein kinase and Ca(2+)-ATPase activity of Malus hupehensis Rhed. roots were studied by adding 3, 3', 4', 5, 7-pentahydroxyflavone (quercetin), a protein kinase inhibitor, and IBA into the Hagland nutrient solution at different time. The results showed that membrane protein phosphorylation in roots occurred mainly on the serine residues. After treatment of Malus hupehensis Rhed.roots with 100 mumol/L IBA, the activity of protein kinase and Ca(2+)-ATPase increased several dozens of times in 2-3 h and then decreased rapidly after they reached the vertex. The protein kinase activity changes earlier than that of Ca(2+)-ATPase. Quercetin not only inhibits the protein kinase activity, but also weakens the activation of Ca(2+)-ATPase by IBA markedly. It is suggested that Ca(2+)-ATPase may be a member of IBA signal transduction in M. hupehensis roots and IBA activates Ca(2+)-ATPase activity through protein phosphorylation.