Figure 3.

A summary of the pathways of chloroplast-nucleus signaling proposed in this article. H, I and D are the ChlH, ChlI and ChlD subunits of Mg-chelatase, respectively; the octagons represent possible receptors for proto IX (pink) and MgProtoME (orange), respectively; the yellow ovals represent unidentified chloroplast envelope proteins involved in signal transduction. Plus and minus signs denote a positive or negative effect on transcription in the nucleus, respectively.