Ubiquitin ligases mediate growth and development by promoting protein death.

The ubiquitin proteasome system (UPS) allows plants to effectively and efficiently alter their proteome so as to ensure developmental plasticity and environmental adaptation. Recent work has demonstrated that the UPS is an integral part of multiple hormone-signaling pathways, which modulate cell growth and differentiation. In response to variation in hormone levels, the UPS regulates the abundance of signaling factors, mainly hormone-responsive transcription factors, which mediate cellular responses. Recent exciting studies have shown that hormones directly or indirectly modulate substrate ubiquitination by regulating E3-substrate interaction. Other avenues of regulation include regulating E3 mRNA abundance.