Salomon M, Zacherl M, Rudiger W
Botanisches Institut der Universitat Munchen, Germany.
Plant Physiol. 1997 Oct;115(2):485-91. doi: 10.1104/pp.115.2.485.
The possible correlation between blue light-dependent phosphorylation of a 116-kD protein and phototropic responses of etiolated oat (Avena sativa L.) seedlings was tested by a micromethod for protein phosphorylation. Quantitation of the basipetal distribution of this protein showed that the in vitro 32p phosphorylation values declined exponentially from tip to node, with more than 50% of the total label being found in the uppermost 5 mm. Nonsaturating preirradiation of the coleoptiles in vivo resulted in partial phosphorylation with endogenous ATP. Subsequent in vitro phosphorylation under saturating irradiation allowed the determination of the degree of in vivo phosphorylation. Unilateral preirradiation resulted in higher in vivo phosphorylation on the irradiated than on the shaded side of the coleoptile. The fluence-response curve for the difference in phosphorylation between both sides of the coleoptile resembles the fluence-response curve for first-positive phototropic curvature, although it is shifted by two orders of magnitude to higher fluences. Possible reasons for this shift are discussed. In the coleoptile base the phosphorylation gradient across the coleoptile becomes larger with increasing time of irradiation at a constant fluence. Thus, phosphorylation of the 116-kD protein, in accordance with second-positive phototropic curvature, does not obey the Bunsen-Roscoe reciprocity law.
采用蛋白质磷酸化微方法，检测了116-kD蛋白的蓝光依赖性磷酸化与黄化燕麦（Avena sativa L.）幼苗向光性反应之间的可能相关性。对该蛋白向基分布的定量分析表明，体外32P磷酸化值从尖端到节部呈指数下降，超过50%的总标记物存在于最上部5mm处。在体内对胚芽鞘进行非饱和预辐照会导致其利用内源性ATP进行部分磷酸化。随后在饱和辐照下进行体外磷酸化，从而能够测定体内磷酸化程度。单侧预辐照导致胚芽鞘受照侧的体内磷酸化高于遮光侧。胚芽鞘两侧磷酸化差异的光通量-反应曲线类似于首次正向光性弯曲的光通量-反应曲线，尽管它向更高光通量方向偏移了两个数量级。文中讨论了这种偏移的可能原因。在胚芽鞘基部，在恒定光通量下，随着辐照时间的增加，胚芽鞘上的磷酸化梯度变得更大。因此，与第二次正向光性弯曲一致，116-kD蛋白的磷酸化不遵循本生-罗斯科互易定律。
