Miller E A, Lee M C, Atkinson A H, Anderson M A
Department of Biochemistry and Genetics, LaTrobe University, Bundoora, Australia.
Plant Mol Biol. 2000 Jan;42(2):329-33. doi: 10.1023/a:1006305429013.
Proteinase inhibitors (PIs) of the potato type II family have been identified in a number of solanaceous species. Most family members have two PI domains which are specific for either chymotrypsin or trypsin. More recently family members have been described with three or six repeated PI domains. Here we describe a novel four-domain family member produced in the stigmas and leaves of the ornamental tobacco, Nicotiana alata, which has high sequence identity with a six-domain member from the same species. Both proteins are produced as precursors that enter the secretory pathway and are subsequently processed into a series of 6 kDa Pis. The four- and six-domain precursor proteins were isolated from immature stigmas and characterised by mass spectrometry which revealed that both proteins had been trimmed at the N-terminus, at a position corresponding to the predicted signal peptide cleavage site. Furthermore, no post-translational modifications were apparent.
在许多茄科物种中已鉴定出马铃薯II型家族的蛋白酶抑制剂（PIs）。大多数家族成员有两个分别对胰凝乳蛋白酶或胰蛋白酶具有特异性的PI结构域。最近，也有具有三个或六个重复PI结构域的家族成员被描述。在此，我们描述了一种在观赏烟草（Nicotiana alata）的柱头和叶片中产生的新型四结构域家族成员，它与来自同一物种的六结构域成员具有高度的序列同一性。这两种蛋白质均以前体形式产生，进入分泌途径，随后被加工成一系列6 kDa的PIs。从未成熟柱头中分离出四结构域和六结构域前体蛋白，并通过质谱进行表征，结果表明这两种蛋白质在N端对应于预测信号肽切割位点的位置被切除。此外，未发现明显的翻译后修饰。
