An intact B890 light-harvesting pigment—protein complex has been obtained from Rhodospirillum rubrum strain S1. We show that this complex contains two types of low-M r polypeptide. Both these polypeptides are present in the intact chromatophore membrane. Analysis of the pigment content of this complex suggests that per pair of polypeptides the complex contains 2 molecules of bacteriochlorophyll and one molecule of carotenoid.
