Auxin response factors (ARFs) are important transcription factors which regulate the expression of auxin response genes in plants and which take on an important role in auxin signal transduction. ARFs can bind specifically to a TGTCTC motif (auxin response element) and mediate auxin responses including activating or inhibiting gene expression. Based on recent advances in the molecular biology of ARFs, structural characteristics as well as biological functions of ARFs and their regulation mechanism are discussed. A typical ARF protein consists of a N-terminal DNA Binding Domain (DBD), a variable middle region that may function as an activation domain (AD) or a repression domain (RD), and one C-terminal Aux/IAA domain (CTD). ARFs promote the transcription of early genes by combining auxin response elements, and they regulate the expression of downstream genes in the process of auxin signal transduction. Different ARFs are expressed in different tissues and organisms. Also, the study of ARF mutants has indicated that different ARFs possess different functions, which are due to differences in temporal and spatial expression and due to affinities with promoters of target genes. Additionally, plant hormones, environmental factors, and non-coding small RNA act as important functions in regulating ARFs. [Ch, 1 fig. 42 ref. ]%生长素响应因子(ARF)是一类调控生长素响应基因表达的转录因子,在生长素的信号传导过程中处于中心位置,它可与生长素响应元件特异结合,促进或抑制基因的表达.介绍了ARF结构特征,生物学功能以及调控机制.植物ARF由3个结构域组成:氨基端的DNA结合结构域(DBD),中间结构域(MR)以及羟基末端的二聚结构域(CTD).中间结构域包括激活结构域(AD)和抑制结构域(RD).在生长素信号转导过程中,ARF主要通过与生长素响应元件结合,促进早期基因转录,从而调节下游基因的表达.不同的ARF在不同的组织和器官中都有特异表达,同时通过ARF突变体的研究表明:不同的ARF具有各自独特的功能.这些功能特异性的产生,既可以来自在时间和空间表达上的不同,也可能是来自对目的基因启动子的亲和性差异.植物激素、外界环境因子和非编码区小RNA对ARF功能的发挥具有重要的调控作用.
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