Isolation of Plastid Ribosomes.

Plastid ribosomes are responsible for a large part of the protein synthesis in plant leaves, green algal cells, and the vast majority in the thalli of red algae. Plastid translation is necessary not only for photosynthesis but also for development/differentiation of plants and algae. While some isolated plastid ribosomes from a few green lineages have been characterized by biochemical and proteomic approaches, in-depth proteomics including analyses of posttranslational modifications and processing, comparative proteomics of plastid ribosomes isolated from the cells grown under different conditions, and those from different taxa are still to be carried out. Establishment of isolation methods for pure plastid ribosomes from a wider range of species would be beneficial to study the relationship between structure, function, and evolution of plastid ribosomes. Here I describe methodologies and provide example protocols for extraction and isolation of plastid ribosomes from a unicellular green alga (Chlamydomonas reinhardtii), a land plant (Arabidopsis thaliana), and a marine red macroalga (Pyropia yezoensis).