Okita T W, Hwang Y S, Hnilo J, Kim W T, Aryan A P, Larson R, Krishnan H B
Institute of Biological Chemistry, Washington State University, Pullman 99164-6340.
J Biol Chem. 1989 Jul 25;264(21):12573-81.
A near full-length cDNA and three genomic clones for rice (Oryza sativa L.) glutelin were isolated and studied. Based on nucleic acid sequence and Southern blot analyses, the three isolated glutelin genomic clones were representative members of three gene subfamilies each containing five to eight copies. A comparison of DNA sequences displayed by relevant regions of these genomic clones showed that two subfamilies, represented by clones Gt1 and Gt2, were closely related and evolved by more recent gene duplication events. The 5'-flanking and coding sequences of Gt1 and Gt2 displayed at least 87% homology. In contrast, Gt3 showed little or no homology in the 5'-flanking sequences upstream of the putative CAAT boxes and exhibited significant divergence in all other portions of the gene. Conserved sequences in the 5'-flanking regions of these genes were identified and discussed in light of their potential regulatory role. The derived primary sequences of all three glutelin genomic clones showed significant homology to the legume 11 S storage proteins indicating a common gene origin. A comparison of the derived glutelin primary sequences showed that mutations were clustered in three peptide regions. One peptide region corresponded to the highly mutable hypervariable region of legume 11 S storage proteins, a potential target area for protein modification. Expression studies indicated that glutelin mRNA transcripts are differentially accumulated during endosperm development. Promoters of Gt2 and Gt3 were functional as they direct transient expression of chloramphenicol acetyltransferase in cultured plant cells.
分离并研究了水稻（Oryza sativa L.）谷蛋白的一个近全长cDNA和三个基因组克隆。基于核酸序列和Southern印迹分析，所分离的三个谷蛋白基因组克隆是三个基因亚家族的代表性成员，每个亚家族包含5至8个拷贝。对这些基因组克隆相关区域所显示的DNA序列进行比较表明，以克隆Gt1和Gt2为代表的两个亚家族密切相关，是通过最近的基因重复事件进化而来的。Gt1和Gt2的5'侧翼序列和编码序列显示出至少87%的同源性。相比之下，Gt3在假定的CAAT框上游的5'侧翼序列中几乎没有同源性，并且在基因的所有其他部分表现出显著的差异。根据这些基因5'侧翼区域的潜在调控作用，对保守序列进行了鉴定和讨论。所有三个谷蛋白基因组克隆的推导一级序列与豆科植物11S贮藏蛋白显示出显著的同源性，表明它们有共同的基因起源。对推导的谷蛋白一级序列进行比较表明，突变集中在三个肽段区域。一个肽段区域对应于豆科植物11S贮藏蛋白的高度可变的高变区，是蛋白质修饰的潜在靶标区域。表达研究表明，谷蛋白mRNA转录本在胚乳发育过程中差异积累。Gt2和Gt3的启动子具有功能，因为它们能在培养的植物细胞中指导氯霉素乙酰转移酶的瞬时表达。
