Higgins T J, Chandler P M, Randall P J, Spencer D, Beach L R, Blagrove R J, Kortt A A, Inglis A S
J Biol Chem. 1986 Aug 25;261(24):11124-30.
Two low molecular weight pea seed albumins (Mr approximately 6000 and approximately 4000) have been characterized by protein, cDNA, and gene sequencing. Both proteins are encoded by separate regions of the same mRNA species. The initial translation product is a preproprotein from which a signal sequence is removed co-translationally. The resultant proprotein (PA1) is then cleaved post-translationally to yield the mature form of the two albumins (PA1a and PA1b). Comparison of cDNA and protein sequences suggests that at least four different PA1 genes are expressed in the pea genome. Both PA1a and PA1b have an unusually high cysteine content (7.5 and 16.2%, respectively). Pea seeds developing under suboptimal levels of sulfur nutrient supply contain reduced levels of PA1 mRNA and accumulate greatly reduced levels of PA1a and PA1b in the mature seed. In vitro transcription studies showed that this reduced level of PA1 mRNA resulted from reduced post-transcriptional stability rather than an altered rate of transcription of the PA1 gene. In contrast, during normal seed development, the level of PA1 mRNA seems to be under transcriptional control. Sequence comparisons reveal some homology between PA1 and a number of low molecular weight proteins from seeds of a wide range of mono- and dicotyledonous plants.
两种低分子量豌豆种子白蛋白（分子量约为6000和约4000）已通过蛋白质、cDNA和基因测序进行了表征。这两种蛋白质由同一mRNA种类的不同区域编码。最初的翻译产物是一种前原蛋白，其信号序列在翻译过程中被共翻译去除。随后，所得的原蛋白（PA1）在翻译后被切割，产生两种白蛋白的成熟形式（PA1a和PA1b）。cDNA和蛋白质序列的比较表明，豌豆基因组中至少有四个不同的PA1基因表达。PA1a和PA1b都具有异常高的半胱氨酸含量（分别为7.5%和16.2%）。在硫营养供应水平次优的条件下发育的豌豆种子，其PA1 mRNA水平降低，成熟种子中PA1a和PA1b的积累水平也大幅降低。体外转录研究表明，PA1 mRNA水平的降低是由于转录后稳定性降低，而不是PA1基因转录速率的改变。相反，在正常种子发育过程中，PA1 mRNA水平似乎受转录控制。序列比较揭示了PA1与多种单子叶和双子叶植物种子中的一些低分子量蛋白质之间存在一些同源性。
