Van Haastert P J
Biochem Biophys Res Commun. 1983 Aug 30;115(1):130-6. doi: 10.1016/0006-291x(83)90979-8.
Chemotactic stimulation of post-vegetative Dictyostelium cells with folic acid or aggregative cells with cAMP results in a fast transient cGMP response which peaks at 10 s; basal levels are recovered in about 30-40 s. Stimulation with folic acid or cAMP rapidly desensitizes the cells for equal or lower concentrated stimuli. However, cells remain responsive for stimuli with higher concentration, which indicates that desensitization is caused by an adaptation process. Removal of the stimulus induces deadaptation, which for both cAMP and folic acid has first order kinetics with a half-life of 1.5 min. Cells were prepared which are simultaneously sensitive to folic acid and to cAMP. The cGMP responses to saturated folic acid and cAMP stimuli are not additive, which suggests that the transduction pathways of these signals meet each other at or before the guanylate cyclase. Cells which are adapted to folic acid are not adapted to cAMP and vice versa. This demonstrates that adaptation of Dictyostelium cells to chemotactic stimuli is localized at a step in the transduction chain before the transduced folic acid and cAMP signals combine in one pathway.
用叶酸对营养期后的盘基网柄菌细胞进行趋化刺激，或用环磷酸腺苷（cAMP）对聚集细胞进行趋化刺激，会导致快速的瞬时环鸟苷酸（cGMP）反应，该反应在10秒时达到峰值；大约在30 - 40秒后恢复到基础水平。用叶酸或cAMP刺激会使细胞对同等浓度或更低浓度的刺激迅速脱敏。然而，细胞对更高浓度的刺激仍有反应，这表明脱敏是由一种适应过程引起的。去除刺激会诱导去适应，对于cAMP和叶酸来说，去适应都具有一级动力学，半衰期为1.5分钟。制备了对叶酸和cAMP同时敏感的细胞。对饱和叶酸和cAMP刺激的cGMP反应不是相加的，这表明这些信号的转导途径在鸟苷酸环化酶处或之前交汇。适应叶酸的细胞对cAMP不适应，反之亦然。这表明盘基网柄菌细胞对趋化刺激的适应定位于转导链中一个步骤，在此之前转导的叶酸和cAMP信号在一条途径中合并。
