Malone Susan, Chen Zhi-Hui, Bahrami Ahmad R, Walker Robert P, Gray Julie E, Leegood Richard C
Robert Hill Institute, University of Sheffield, Sheffield S10 2TN, UK.
Plant Cell Physiol. 2007 Mar;48(3):441-50. doi: 10.1093/pcp/pcm014. Epub 2007 Feb 5.
The aim of this work was to investigate the occurrence of phosphoenolpyruvate carboxykinase (PEPCK) in different tissues of Arabidopsis thaliana throughout its vegetative and reproductive growth. The A. thaliana genome contains two PEPCK genes (PCK1 and PCK2), and these are predicted to generate 73,404 and 72,891 Da protein products, respectively. Both genes were transcribed in a range of tissues; however, PCK1 mRNA appeared to be more abundant and was present in a wider range of tissues. PEPCK protein was present in flowers, fruit, developing seed, germinating seed, leaves, stems and roots. Two PEPCK polypeptides, of approximately 74 and approximately 73 kDa were detected by immunoblotting, and these may arise from PCK1 and PCK2, respectively. PEPCK was abundant in cotyledons during post-germinative growth, and this is consistent with its well established role in gluconeogenesis. PEPCK was also abundant in sink tissues, such as young leaves, in developing flowers, fruit and seed. Immunohistochemistry and in situ hybridization showed that PEPCK was present in the nectaries, stigma, endocarp of the fruit wall and in tissues involved in the transfer of assimilates to the developing ovules and seeds, such as the vasculature and seed coat. The potential functions of PEPCK in A. thaliana are discussed.
这项工作的目的是研究磷酸烯醇式丙酮酸羧激酶（PEPCK）在拟南芥营养生长和生殖生长的不同组织中的存在情况。拟南芥基因组包含两个PEPCK基因（PCK1和PCK2），预计它们分别产生73,404 Da和72,891 Da的蛋白质产物。这两个基因在一系列组织中都有转录；然而，PCK1 mRNA似乎更为丰富，且存在于更广泛的组织中。PEPCK蛋白存在于花、果实、发育中的种子、萌发的种子、叶、茎和根中。通过免疫印迹检测到两种PEPCK多肽，分子量分别约为74 kDa和约73 kDa，它们可能分别来自PCK1和PCK2。在萌发后生长过程中，子叶中PEPCK含量丰富，这与其在糖异生中已确立的作用一致。PEPCK在库组织中也很丰富，如幼叶、发育中的花、果实和种子。免疫组织化学和原位杂交表明，PEPCK存在于蜜腺、柱头、果实壁的内果皮以及参与同化物向发育中的胚珠和种子转运的组织中，如脉管系统和种皮。文中讨论了PEPCK在拟南芥中的潜在功能。
