Ceccarelli A, McRobbie S J, Jermyn K A, Duffy K, Early A, Williams J G
Imperial Cancer Research Fund, Clare Hall Laboratories, Hertfordshire, UK.
Nucleic Acids Res. 1987 Sep 25;15(18):7463-76. doi: 10.1093/nar/15.18.7463.
The pDd56 mRNA sequence is highly enriched in prestalk over prespore cells and is inducible by DIF, the putative Dictyostelium stalk-specific morphogen. We show that the pDd56 gene is composed of forty one copies of a twenty four amino acid, cysteine rich repeat. This is highly homologus to a repeat which we have previously shown to compose the major fraction of the pDd63 mRNA, another DIF inducible, prestalk-enriched sequence. The predicted pDd56 protein contains a putative signal peptide but does not appear to contain a transmembrane segment. In combination these features suggest it to be an extrinsic protein and we confirm this elsewhere by showing that the pDd56 gene encodes a known, extracellular protein of the stalk. The pDd56 mRNA is dependent upon exogenous DIF for its accumulation. We show that this control is exerted at the transcriptional level and that a restriction fragment containing 1.7Kb of upstream sequence directs temporally-regulated expression of the gene.
pDd56 mRNA序列在前柄细胞中比前孢子细胞高度富集，并且可被DIF（假定的盘基网柄菌柄特异性形态发生素）诱导。我们发现pDd56基因由41个24个氨基酸的富含半胱氨酸的重复序列组成。这与我们之前发现的构成pDd63 mRNA主要部分的重复序列高度同源，pDd63 mRNA是另一个DIF诱导的、在前柄中富集的序列。预测的pDd56蛋白含有一个假定的信号肽，但似乎不包含跨膜区段。综合这些特征表明它是一种外在蛋白，我们在其他地方通过证明pDd56基因编码一种已知的柄细胞外蛋白来证实这一点。pDd56 mRNA的积累依赖于外源性DIF。我们表明这种调控是在转录水平上发挥作用的，并且一个包含1.7Kb上游序列的限制片段指导该基因的时间调控表达。
