Editing Pyrenoid (section)

==Physiology and regulation of the CCM==

The algal CCM is inducible, and induction of the CCM is generally the result of low CO<sub>2</sub> conditions. Induction and regulation of the ''Chlamydomonas'' CCM was recently studied by transcriptomic analysis, revealing that one out of three genes are up- or down-regulated in response to changed levels of CO<sub>2</sub> in the environment.<ref>Brueggeman, A. J., Gangadharaiah, D. S., Cserhati, M. F., Casero, D., Weeks, D. P., & Ladunga, I. (2012). Activation of the carbon concentrating mechanism by CO<sub>2</sub> deprivation coincides with massive transcriptional restructuring in ''Chlamydomonas reinhardtii''. The Plant Cell, 24(5), 1860-1875 {{PMID|22634764}}</ref> Sensing of CO<sub>2</sub> in ''Chlamydomonas'' involves a “master switch”, which was co-discovered by two laboratories.<ref>Xiang, Y., Zhang, J., & Weeks, D. P. (2001). The Cia5 gene controls formation of the carbon concentrating mechanism in ''Chlamydomonas reinhardtii''. ''Proceedings of the National Academy of Sciences'', 98(9), 5341-5346 {{PMID|11309511}}</ref><ref>Fukuzawa, H., Miura, K., Ishizaki, K., Kucho, K. I., Saito, T., Kohinata, T., & Ohyama, K. (2001). Ccm1, a regulatory gene controlling the induction of a carbon-concentrating mechanism in ''Chlamydomonas reinhardtii'' by sensing CO<sub>2</sub> availability. ''Proceedings of the National Academy of Sciences'', 98(9), 5347-5352. {{PMID|11287669}}</ref> This gene, Cia5/Ccm1, affects over 1,000 CO<sub>2</sub>-responsive genes<ref>Fang, W., Si, Y., Douglass, S., Casero, D., Merchant, S. S., Pellegrini, M., ... & Spalding, M. H. (2012). Transcriptome-wide changes in ''Chlamydomonas reinhardtii'' gene expression regulated by carbon dioxide and the CO<sub>2</sub>-concentrating mechanism regulator CIA5/CCM1. The Plant Cell, 24(5), 1876-1893. {{PMID|22634760}}</ref> and also conditions the degree of packing of RuBisCO into the pyrenoid.