Kaleko M, Rothman F G
Cell. 1982 Apr;28(4):801-11. doi: 10.1016/0092-8674(82)90059-9.
Postaggregative gene expression in Dictyostelium discoideum requires cell contact. Polyspecific monovalent antibodies (Fab) prepared from sera raised against membranes of aggregation- and postaggregation-stage cells were used to probe the cell interactions that induce rapid postaggregative synthesis of UDP-glucose pyrophosphorylase. When cells of strain V12M2 were dissociated after 8 hr of development and replated in the presence of immune Fab, both reaggregation and pyrophosphorylase synthesis were blocked. Fab neutralized by incubation with EDTA-high salt extracts of cells developed for 3 hr blocked pyrophosphorylase synthesis but not reaggregation. Therefore, some cell-surface components that regulate pyrophosphorylase synthesis (called E sites) are antigenically distinct from those required for reaggregation. The Fab provides a means to assay E sites during their purification. Addition of 10(-3) M cyclic AMP or cyclic GMP enabled the cells to bypass the blocking of E sites by Fab; pyrophosphorylase was synthesized in the absence of reaggregation. We hypothesize that E sites function by raising the level of intracellular cyclic AMP.
盘基网柄菌聚合后的基因表达需要细胞接触。用从针对聚集期和聚集后期细胞的膜制备的血清中获得的多特异性单价抗体（Fab）来探究诱导UDP - 葡萄糖焦磷酸化酶快速聚集后合成的细胞相互作用。当V12M2菌株的细胞在发育8小时后解离，并在免疫Fab存在的情况下重新接种时，再聚集和焦磷酸化酶的合成均被阻断。与发育3小时的细胞的EDTA - 高盐提取物孵育而中和的Fab阻断了焦磷酸化酶的合成，但未阻断再聚集。因此，一些调节焦磷酸化酶合成的细胞表面成分（称为E位点）在抗原性上与再聚集所需的成分不同。Fab提供了一种在纯化过程中检测E位点的方法。添加10⁻³ M的环磷酸腺苷（cAMP）或环磷酸鸟苷苷（cGMP可使细胞绕过Fab对E位点的阻断；在没有再聚集的情况下合成了焦磷酸化酶。我们假设E位点通过提高细胞内环磷酸腺苷的水平发挥作用。
