Laskowski Marta
Biology Department, Oberlin College, Oberlin, OH 44074, USA.
Sci STKE. 2006 Feb 14;2006(322):tr1. doi: 10.1126/stke.3222006tr1.
Auxin mediates numerous plant responses, some of which have been shown to require transcriptional regulation. One auxin response pathway, which depends on the relief of transcriptional repression, is mediated by TIR1 (transport inhibitor response protein 1). TIR1 is an auxin receptor and also a subunit of an SCF-type ubiquitin ligase. In the presence of a low concentration of auxin in the nucleus, members of the Aux/IAA family of transcriptional repressors bind to ARF proteins and inhibit the transcription of specific auxin response genes. Increased nuclear concentrations of auxin promote auxin binding to TIR1, causing the Aux/IAA proteins to associate with TIR1 and leading to their degradation by a proteasome-mediated pathway. This decreases the concentration of Aux/IAA proteins in the nucleus and thereby enables the expression of certain auxin response genes.
生长素介导多种植物反应，其中一些反应已被证明需要转录调控。一种依赖于转录抑制解除的生长素反应途径由TIR1（运输抑制剂反应蛋白1）介导。TIR1是一种生长素受体，也是SCF型泛素连接酶的一个亚基。在细胞核中存在低浓度生长素的情况下，转录抑制因子Aux/IAA家族的成员与ARF蛋白结合，并抑制特定生长素反应基因的转录。细胞核中生长素浓度的增加促进生长素与TIR1结合，导致Aux/IAA蛋白与TIR1结合，并通过蛋白酶体介导的途径导致其降解。这降低了细胞核中Aux/IAA蛋白的浓度，从而使某些生长素反应基因得以表达。
