The F-box protein
COI1 (CORONATINE INSENSITIVE 1 ) is a key regulator
of the JA signaling pathway (Chung et al. 2009).
It functions as a JA-Ile receptor in the E3 ubiquitin-ligase
Skip-Cullin-F-box complex SCFCOI1 (Yan et al. 2009).
Binding of JA-Ile to COI1 leads to degradation of JASMONATE
ZIM-domain (JAZ) transcriptional repressor
proteins via the proteasome (Chini et al. 2007; Thines et al.
2007). In resting cells, JAZ proteins act as transcriptional
repressors of JA signaling by binding to positive transcriptional
regulators, such as MYC2 (Chini et al. 2007).
Hence, JAZ protein degradation results in de-repression of
the JA signaling pathway and the activation of a large
number of JA-responsive genes (Memelink 2009).