Figure 9.

Model for the regulation of GLK1 by multiple mechanisms. Both developmental signals and Suc regulate the accumulation of GLK1 protein through transcriptional regulation of GLK1 gene. Plastid signals derived from damaged plastids also regulate the expression of GLK1 through the activity of GUN1. Meanwhile, plastid signals regulate the accumulation of GLK1 at protein level. Although the components involved in this regulation remain to be identified, the ubiquitin-proteasome system appears to participate in this regulation.