Teaching resources. Model of the TIR1 pathway for auxin-mediated gene expression.
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.
Laskowski
Marta
M
Biology Department, Oberlin College, Oberlin, OH 44074, USA. mlaskows@oberlin.edu
D029681:Arabidopsis Proteins / Q000502:physiology*; D001901:Botany / Q000193:education*; D044783:F-Box Proteins / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D007210:Indoleacetic Acids / Q000378:metabolism*; D008954:Models, Biological; D009040:Motion Pictures; D010940:Plant Proteins / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology*; D012097:Repressor Proteins / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*
D029681:Arabidopsis Proteins; D044783:F-Box Proteins; D007210:Indoleacetic Acids; D010940:Plant Proteins; D011956:Receptors, Cell Surface; D012097:Repressor Proteins; C501405:TIR1 protein, Arabidopsis; C046131:auxin receptor, plant