A 160Â kDa protein with carbonic anhydrase activity is complexed with rubisco on the outer surface of thylakoids

This study provides evidence that, in the soluble fraction from buffer-washed pea thylakoids, one form of soluble carbonic anhydrase (CA) is associated with rubisco in a stromal protein complex. On native-PAGE gels, it is present as a protein band with MW approximately 160 kDa. On SDS-PAGE gels, it is resolved as a single 25-kDa polypeptide. Analysis of Western blots developed with polyclonal antibodies to barley rubisco and to soluble pea CA shows that a 160-kDa protein with CA activity is associated with rubisco in a protein complex localized on the outer surface of thylakoid membranes.