A protein found in plant cells that binds auxins and thus may act as the initial receptor of the signal transduction pathway for these plant hormones. Likely candidates have been found in various plant tissue cultures, including pith cells of tobacco and coleoptile tissue of maize. A receptor for auxin has been identified. It is a protein called TIR1 (transport inhibitor response 1), found in the nucleus. Binding of auxin to TIR1 leads to the degradation of certain repressors of gene transcription, which allows genes to be ‘switched on’. Another possible auxin-binding protein is called ABP1, but its precise role remains uncertain. See also acid growth theory.
Subjects: Biological Sciences — Chemistry.