Adams D S, Noonan D, Jeffery W R
Differentiation. 1981;20(3):177-87. doi: 10.1111/j.1432-0436.1981.tb01174.x.
Starvation induces vegetative microplasmodia of Physarum polycephalum to differentiate into translationally-dormant sclerotia. The existence and the biochemical nature of stored mRNA in sclerotia is examined in this report. The sclerotia contain about 50% of the poly (A)-containing RNA [poly(A)+RNA] complement of microplasmodia as determined by [3H]-poly(U) hybridization. The sclerotial poly(A)+RNA sequences are associated with proteins in a ribonucleoprotein complex [poly(A)+mRNP] which sediments more slowly than the polysomes. Sclerotial poly(A)+RNP sediments more rapidly than poly(A)+RNP derived from the polysomes of microplasmodia despite the occurrence of poly(A)+RNA molecules of a similar size in both particles suggesting the existence of differences in protein composition. Isolation of poly(A)+RNP by oligo (dT)-cellulose chromatography and the analysis of its associated proteins by polyacrylamide gel electrophoresis show that sclerotial poly(A)+RNP contains at least 14 major polypeptides, 11 of which are different in electrophoretic mobility from the polypeptides found in polysomal poly(A)+RNP. Three of the sclerotial poly(A)+RNP polypeptides are associated with the poly(A) sequence (18, 46, and 52 x 10(3) mol. wt. components), while the remaining eight are presumably bound to non-poly(A) portions of the poly(A)+RNA. Although distinct from polysomal poly(A)+RNP, the sclerotial poly(A)+RNP is similar in sedimentation behavior and protein composition (with two exceptions) to the microplasmodial free cytoplasmic poly(A)+RNP. The results suggest that dormant sclerotia store mRNA sequences in association with a distinct set of proteins and that these proteins are similar to those associated with the free cytoplasmic poly(A)+RNP of vegetative plasmodia.
饥饿诱导多头绒泡菌的营养型微原质团分化为翻译休眠的菌核。本报告研究了菌核中储存mRNA的存在情况及其生化性质。通过[³H]-聚（U）杂交测定，菌核含有微原质团约50%的含聚腺苷酸RNA[聚（A）⁺RNA]。菌核聚（A）⁺RNA序列与核糖核蛋白复合物[聚（A）⁺mRNP]中的蛋白质相关联，该复合物的沉降速度比多核糖体慢。尽管两种颗粒中存在大小相似的聚（A）⁺RNA分子，但菌核聚（A）⁺RNP的沉降速度比源自微原质团多核糖体的聚（A）⁺RNP快，这表明蛋白质组成存在差异。通过寡聚（dT）-纤维素色谱法分离聚（A）⁺RNP，并通过聚丙烯酰胺凝胶电泳分析其相关蛋白质，结果表明菌核聚（A）⁺RNP含有至少14种主要多肽，其中11种在电泳迁移率上与多核糖体聚（A）⁺RNP中的多肽不同。菌核聚（A）⁺RNP的三种多肽与聚（A）序列相关（分子量分别为18、46和52×10³的组分），而其余八种可能与聚（A）⁺RNA的非聚（A）部分结合。尽管与多核糖体聚（A）⁺RNP不同，但菌核聚（A）⁺RNP在沉降行为和蛋白质组成（有两个例外）方面与微原质团游离细胞质聚（A）⁺RNP相似。结果表明，休眠菌核储存与一组独特蛋白质相关的mRNA序列，并且这些蛋白质与营养型原质团的游离细胞质聚（A）⁺RNP相关的蛋白质相似。
