Life on Earth depends on photosynthetic carbon dioxide (CO2) fixation to form organic carbon. Plants take atmospheric CO2 and transform it into organic molecules such as glucose. This process evolved in cyanobacteria and was later conveyed to eukaryotes, giving rise to plastids in algae and plants. Researchers have now discovered a new protein which is involved in this complex process; it regulates the intake of CO2 into the cell. Khaled Selim and Professor Karl Forchhammer from the Interfaculty Institute for Microbiology and Infection Medicine (IMIT), together with colleagues from the Max-Planck Institute for Proteinevolution and from the University Rostock, describe their finding of the conserved cyclic AMP receptor protein, SbtB, in the latest edition of Proceedings of the National Academy of Sciences (PNAS).