Kinoshita T, Nishimura M, Hara-Nishimura I
Department of Cell Biology, National Institute for Basic Biology, Okazaki, Japan.
Plant Mol Biol. 1995 Oct;29(1):81-9. doi: 10.1007/BF00019120.
Vacuolar processing enzymes (VPEs) are responsible for the maturation of seed proteins. These processing enzymes belong to a novel group of cysteine proteinases with molecular masses of 37 to 39 kDa. We isolated two genes of VPEs from a genomic library of Arabidopsis. The gene products were designated alpha-VPE and beta-VPE, and they were 56% identical in terms of amino acid sequence. The amino acid sequences of alpha-VPE and beta-VPE were also 55% and 67% identical to that of castor bean VPE, respectively. The gene for alpha-VPE had 7 introns, while that of beta-VPE had 8 introns. Northern blot analysis revealed that alpha-VPE is expressed in rosette leaves, cauline leaves and stems of Arabidopsis, while beta-VPE is predominantly expressed in the flowers and buds. Neither alpha-VPE nor beta-VPE is expressed in the siliques. This result strongly suggests that the isolated genes encode isozymes of VPE that are specific to vegetative organs.
液泡加工酶（VPEs）负责种子蛋白的成熟。这些加工酶属于一类新型的半胱氨酸蛋白酶，分子量为37至39 kDa。我们从拟南芥基因组文库中分离出两个VPEs基因。基因产物分别命名为α-VPE和β-VPE，它们的氨基酸序列有56%的同一性。α-VPE和β-VPE的氨基酸序列与蓖麻VPE的氨基酸序列也分别有55%和67%的同一性。α-VPE基因有7个内含子，而β-VPE基因有8个内含子。Northern印迹分析表明，α-VPE在拟南芥的莲座叶、茎生叶和茎中表达，而β-VPE主要在花和芽中表达。α-VPE和β-VPE在角果中均不表达。这一结果强烈表明，分离出的基因编码的是营养器官特有的VPE同工酶。
