Gallego P P, Whotton L, Picton S, Grierson D, Gray J E
Lab. Fisiología Vegetal, Universidad de Vigo, Spain.
Plant Mol Biol. 1995 Mar;27(6):1143-51. doi: 10.1007/BF00020887.
A tomato fruit cDNA library was differentially screened to identify mRNAs present at higher levels in fruit of the tomato ripening mutant rin (ripening inhibitor). Complete sequencing of a unique clone ERT D1 revealed an open reading frame with homology to several glutamate decarboxylases. The deduced polypeptide sequence has 80% overall amino acid sequence similarity to a Petunia hybrida glutamate decarboxylase (petGAD) which carries a calmodulin-binding site at its carboxyl terminus and ERT D1 appears to have a similar domain. ERT D1 mRNA levels peaked at the first visible sign of fruit colour change during normal tomato ripening and then declined, whereas in fruit of the ripening impaired mutant, rin, accumulation of this mRNA continued until at least 14 days after the onset of ripening. This mRNA was present at much lower levels in other tissues, such as leaves, roots and stem, and was not increased by wounding. Possible roles for GAD, and its product gamma-aminobutyric acid (GABA) in fruit, are discussed.
通过差异筛选番茄果实cDNA文库，以鉴定番茄成熟突变体rin（成熟抑制剂）果实中高水平存在的mRNA。对一个独特克隆ERT D1进行全序列分析，发现一个与几种谷氨酸脱羧酶具有同源性的开放阅读框。推导的多肽序列与矮牵牛谷氨酸脱羧酶（petGAD）的总体氨基酸序列相似性为80%，petGAD在其羧基末端带有一个钙调蛋白结合位点，ERT D1似乎也有类似结构域。在正常番茄成熟过程中，ERT D1 mRNA水平在果实颜色变化的第一个可见迹象时达到峰值，然后下降，而在成熟受损的突变体rin的果实中，这种mRNA的积累一直持续到成熟开始后至少14天。该mRNA在其他组织如叶、根和茎中的含量要低得多，且不受创伤诱导增加。文中讨论了GAD及其产物γ-氨基丁酸（GABA）在果实中的可能作用。
