Wessels D, Schroeder N A, Voss E, Hall A L, Condeelis J, Soll D R
Department of Biology, University of Iowa, Iowa City 52242.
J Cell Biol. 1989 Dec;109(6 Pt 1):2841-51. doi: 10.1083/jcb.109.6.2841.
Before addition of cAMP, Dictyostelum amoebae rapidly translocating in buffer are elongate, exhibit expansion zones primarily at the anterior end and filamentous actin (F-actin) localization primarily in the anterior pseudopodia. Intracellular particle movement is primarily in the anterior direction, and the average rate of particle movement is roughly five times the rate of cellular translocation. Within seconds after the addition of 10(-6)M cAMP, there is a dramatic suppression of cellular translocation, an inhibition of pseudopod formation, a freeze in cellular morphology, a dramatic depression in intracellular particle movement, loss of F-actin localization in pseudopodia concomitant with relocalization of F-actin in the general cytoplasmic cortex under the plasma membrane, and a doubling of F-actin content. After 10 s, expansion zones are again visible at the cell perimeter, but they no longer are localized in the original anterior portion of the cell. There is a slight rebound in particle movement after 10 s, but particles with persistent tracks now show no directionality towards the original anterior portion of the cell, as they did before cAMP addition. Finally, in parallel with the resumption of peripheral expansion and the small rebound in particle movement, there is a decrease in total cellular F-actin to the untreated level. The pattern of microtubule organization is unaffected by the addition of cAMP.
在添加环磷酸腺苷（cAMP）之前，在缓冲液中快速移动的盘基网柄菌变形虫呈细长形，主要在前端出现扩张区，丝状肌动蛋白（F-肌动蛋白）主要定位于前端伪足。细胞内颗粒运动主要向前，颗粒运动的平均速率约为细胞移动速率的五倍。在添加10⁻⁶M cAMP后的几秒钟内，细胞移动受到显著抑制，伪足形成受到抑制，细胞形态冻结，细胞内颗粒运动急剧下降，伪足中F-肌动蛋白定位丧失，同时F-肌动蛋白重新定位于质膜下的一般细胞质皮层，F-肌动蛋白含量增加一倍。10秒后，细胞周边再次可见扩张区，但不再位于细胞原来的前端部分。10秒后颗粒运动略有反弹，但有持续轨迹的颗粒现在不再像添加cAMP之前那样朝着细胞原来的前端部分显示方向性。最后，与外周扩张的恢复和颗粒运动的小反弹同时，细胞总F-肌动蛋白减少至未处理水平。微管组织模式不受添加cAMP的影响。
