Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
PLoS One. 2010 Jan 6;5(1):e8542. doi: 10.1371/journal.pone.0008542.
During seed germination, beta-conglutin undergoes a major cycle of limited proteolysis in which many of its constituent subunits are processed into a 20 kDa polypeptide termed blad. Blad is the main component of a glycooligomer, accumulating exclusively in the cotyledons of Lupinus species, between days 4 and 12 after the onset of germination.
The sequence of the gene encoding beta-conglutin precursor (1791 nucleotides) is reported. This gene, which shares 44 to 57% similarity and 20 to 37% identity with other vicilin-like protein genes, includes several features in common with these globulins, but also specific hallmarks. Most notable is the presence of an ubiquitin interacting motif (UIM), which possibly links the unique catabolic route of beta-conglutin to the ubiquitin/proteasome proteolytic pathway.
Blad forms through a unique route from and is a stable intermediary product of its precursor, beta-conglutin, the major Lupinus seed storage protein. It is composed of 173 amino acid residues, is encoded by an intron-containing, internal fragment of the gene that codes for beta-conglutin precursor (nucleotides 394 to 913) and exhibits an isoelectric point of 9.6 and a molecular mass of 20,404.85 Da. Consistent with its role as a storage protein, blad contains an extremely high proportion of the nitrogen-rich amino acids.
在种子萌发过程中，β-伴球蛋白经历了一个主要的有限蛋白水解循环，其中其许多组成亚基被加工成一种 20 kDa 的多肽，称为 blad。Blad 是糖脂寡聚物的主要成分，仅在发芽后第 4 天至第 12 天在羽扇豆属植物的子叶中积累。
报道了编码β-伴球蛋白前体的基因序列（1791 个核苷酸）。该基因与其他类豆球蛋白蛋白基因的相似性为 44%至 57%，同一性为 20%至 37%，与其他球蛋白有几个共同特征，但也有特定的标志。最值得注意的是存在泛素相互作用基序（UIM），它可能将β-伴球蛋白的独特分解途径与泛素/蛋白酶体蛋白水解途径联系起来。
Blad 是通过其前体β-伴球蛋白的独特途径形成的，并且是其稳定的中间产物，β-伴球蛋白是羽扇豆属种子的主要贮藏蛋白。它由 173 个氨基酸残基组成，由编码β-伴球蛋白前体（核苷酸 394 至 913）的基因的包含内含子的内部片段编码，其等电点为 9.6，分子量为 20404.85 Da。与作为贮藏蛋白的作用一致，blad 含有极高比例的富含氮的氨基酸。
