National Center for Biotechnology Information

The most important plastids, the chloroplasts, function in trapping the energy of sunlight during photosynthesis. They are disk-shaped structures with a platelike arrangement of tightly stacked membranes. Read More function in algae In protist: Respiration and nutrition

9 Plastid-to-Nucleus Signaling 183–197 Asa Strand, Tatjana Kleine and Joanne Chory˚ Summary 183 I. Introduction 184 II. Intracellular Communication During Chloroplast Development 184 III. Retrograde Communication Through “Plastid Signals” 185 IV. Mg-ProtoIX, a Link Between the Plastids and the Nucleus 189

Plastids are remnants of a photosynthetic organism that was engulfed by the host, although not all are now photosynthetic. Plastid genomes encode genes for rRNAs, tRNAs and between about 28 and 150 proteins. Plastids can be categorized into 4 main groups: chloroplasts, cyanelles, apicoplasts and non-photosynthetic.