Berlot C H, Spudich J A, Devreotes P N
Cell. 1985 Nov;43(1):307-14. doi: 10.1016/0092-8674(85)90036-4.
Cyclic AMP stimulation of chemotactically competent Dictyostelium amebas labeled with [32P]orthophosphate transiently increases phosphorylation in the heavy chain and the 18,000 dalton light chain of myosin. Immediately before the increase, heavy chain phosphorylation transiently decreases. These phosphorylation changes also occur when cAMP-induced activation of adenylate cyclase is blocked by pretreatment of amebas with caffeine. The time course of these phosphorylation responses correlates with the shape changes induced in amebas exposed to a temporal increase in cAMP concentration. The dose dependence of the phosphorylation responses is the same as that previously determined for chemotaxis. The phosphorylation responses exhibit adaptation properties in common with those of the shape change response and chemotaxis. Increases in the rate of myosin heavy chain and light chain phosphorylation can be observed in vitro by stimulating unlabeled amebas with cAMP and then lysing the cells into a gamma-[32P]ATP-containing reaction mixture.
用[32P]正磷酸盐标记的趋化性成熟的盘基网柄菌变形虫经环磷酸腺苷（cAMP）刺激后，肌球蛋白重链和18000道尔顿轻链的磷酸化作用会短暂增加。在增加之前，重链磷酸化会短暂减少。当用咖啡因预处理变形虫来阻断cAMP诱导的腺苷酸环化酶激活时，也会发生这些磷酸化变化。这些磷酸化反应的时间进程与暴露于cAMP浓度随时间增加的变形虫中诱导产生的形状变化相关。磷酸化反应的剂量依赖性与先前确定的趋化作用相同。磷酸化反应表现出与形状变化反应和趋化作用相同的适应性特性。通过用cAMP刺激未标记的变形虫，然后将细胞裂解到含γ-[32P]ATP的反应混合物中，可在体外观察到肌球蛋白重链和轻链磷酸化速率的增加。
