Figure 5.

Model for Ethylene Signal Transduction.In air, ethylene receptors maintain CTR1 in an active state that serves to repress ethylene responses. In ethylene, the repression is relieved. Binding of ethylene inactivates the receptors, thereby inactivating CTR1. As a result, EIN2 is activated and a transcriptional cascade involving the EIN3/EIL and ERF transcription factors is initiated. Both families of transcription factors are involved in regulating ethylene responses. Soluble protein domains are shown as circles. The predicted transmembrane structures are shown for the ethylene receptors and EIN2. Location of pathway components is shown where known.