Rödin J, Ericson M L, Josefsson L G, Rask L
Department of Cell Research, Swedish University of Agricultural Sciences, Uppsala Biomedical Center, Sweden.
J Biol Chem. 1990 Feb 15;265(5):2720-3.
Cruciferin (12 S globulin) is a large, neutral, oligometric protein synthesized in rapeseed (Brassica napus) during seed development. It is the major seed protein and is composed of six subunit pairs. Each of these pairs is synthesized as a precursor containing one heavy alpha-chain and one light beta-chain. Electrophoretic analysis of cruciferin showed that four different alpha- and four different beta-chains exist. A cruciferin clone was selected from an embryo cDNA library. This clone, pCRU1, contains a 1518-base pair open reading frame corresponding to a truncated NH2-terminal signal sequence followed by an alpha-chain of 296 and a beta-chain of 190 amino acid residues. Individual cruciferin chains as well as peptides thereof were subjected to NH2-terminal amino acid sequence analysis. The sequences obtained from a specific alpha- and beta-chain pair (alpha 1 and beta 1) showed total identity with the deduced amino acid sequence from pCRU1. Further comparisons revealed that a previously characterized cruciferin cDNA clone encodes one of the precursors for the closely related alpha 2/ alpha 3-beta 2/beta 3 subunits. The deduced amino acid sequences of the two cDNA clones display 64% similarity.
十字花科素（12S球蛋白）是一种在油菜籽（甘蓝型油菜）种子发育过程中合成的大型、中性、寡聚蛋白。它是主要的种子蛋白，由六个亚基对组成。这些亚基对中的每一个都是作为含有一条重α链和一条轻β链的前体合成的。十字花科素的电泳分析表明存在四种不同的α链和四种不同的β链。从胚胎cDNA文库中筛选出一个十字花科素克隆。这个克隆pCRU1包含一个1518个碱基对的开放阅读框，对应于一个截短的NH2末端信号序列，后面跟着一条由296个氨基酸残基组成的α链和一条由190个氨基酸残基组成的β链。对单个十字花科素链及其肽段进行了NH2末端氨基酸序列分析。从特定的α链和β链对（α1和β1）获得的序列与从pCRU1推导的氨基酸序列完全一致。进一步比较发现，一个先前鉴定的十字花科素cDNA克隆编码密切相关的α2/α3-β2/β3亚基的前体之一。这两个cDNA克隆推导的氨基酸序列显示出64%的相似性。
