The plant N-end rule pathway: structure and functions

The N-end rule pathway is a protein degradation pathway that relates the stability of a protein to the nature of its N-terminal amino acid residue. This pathway is part of the ubiquitin–proteasome system in eukaryotes and has been shown to be involved in a multitude of cellular and developmental processes in animals and fungi. However, in plants, its structure and functions have long been enigmatic. In this review, we discuss recent advances in the identification of the enzymatic components that mediate protein degradation through the N-end rule pathway in plants. We further describe the known functions of this pathway in the control of plant growth and development and outline open questions that will likely be the focus of future research