Thoma S, Sullivan M L, Vierstra R D
Department of Horticulture, University of Wisconsin-Madison 53706, USA.
Plant Mol Biol. 1996 Jun;31(3):493-505. doi: 10.1007/BF00042223.
Covalent attachment of ubiquitin to other intracellular proteins is essential for many physiological processes in eukaryotes, including selective protein degradation. Selection of proteins for ubiquitin conjugation is accomplished, in part, by a group of enzymes designated E2s or ubiquitin-conjugating enzymes (UBCs). At least six types of E2s have been identified in the plant Arabidopsis thaliana; each type is encoded by a small gene family. Previously, we described the isolation and characterization of two three-member gene families, designated AtUBC1-3 and AtUBC4-6, encoding two of these E2 types. Here, we investigated the expression patterns, of the AtUBC1-3 and AtUBC4-6 genes by the histochemical analysis of transgenic Arabidopsis containing the corresponding promoters fused to the beta-glucuronidase-coding region. Staining patterns showed that these genes are active in many stages of development and some aspects of cell death, but are not induced by heat stress. Within the two gene families, individual members exhibited both overlapping and complementary expression patterns, indicating that at least one member of each gene family is expressed in most cell types and at most developmental stages. Different composite patterns of expression were observed between the AtUBC1-3 and AtUBC4-6 families, suggesting distinct biochemical and/or physiological functions for the encoded E2s in Arabidopsis.
泛素与其他细胞内蛋白质的共价连接对于真核生物中的许多生理过程至关重要，包括选择性蛋白质降解。蛋白质的泛素化选择部分由一组称为E2或泛素结合酶（UBC）的酶完成。在植物拟南芥中已鉴定出至少六种类型的E2；每种类型由一个小基因家族编码。此前，我们描述了两个由三个成员组成的基因家族AtUBC1 - 3和AtUBC4 - 6的分离和特征，它们编码其中两种E2类型。在这里，我们通过对含有与β - 葡萄糖醛酸酶编码区融合的相应启动子的转基因拟南芥进行组织化学分析，研究了AtUBC1 - 3和AtUBC4 - 6基因的表达模式。染色模式表明，这些基因在发育的许多阶段和细胞死亡的某些方面都有活性，但不受热应激诱导。在这两个基因家族中，各个成员表现出重叠和互补的表达模式，表明每个基因家族的至少一个成员在大多数细胞类型和大多数发育阶段都有表达。在AtUBC1 - 3和AtUBC4 - 6家族之间观察到不同的复合表达模式，这表明拟南芥中编码的E2具有不同的生化和/或生理功能。
