bacterial microcompartment carboxysome https://github.com/geneontology/go-ontology/issues/19743 An organelle consisting of a proteinaceous coat and enzymes for the fixation of CO2. It augments the concentration of CO2 in the vicinity of RuBisCO to increase the efficiency of CO2 fixation under atmospheric conditions. GO:0031470 Wikipedia:Carboxysome cellular_component