title: Core substructure in cyanobacterial phycobilisomes.
abstract: The tricylindrical core of Synechocystis 6701 phycobilisomes is made up of four types of allophycocyanin-containing complexes: A, (alpha AP beta AP)3; B, (alpha AP beta AP)3 .10K; C, (alpha APB1 alpha AP2 beta AP3).10K; D, (alpha AP beta AP)2.18.5K.99K; where AP is allophycocyanin, APB is allophycocyanin B, and 10K, 18.5K, and 99K are polypeptides of 10,000, 18,500, and 99,000 daltons, respectively. The 18.5K polypeptide is a hitherto unrecognized biliprotein subunit with a single phycocyanobilin prosthetic group. The tricylindrical core is made up of 12 subcomplexes in the molar ratio of A:B:C:D: of 4:4:2:2. Complexes C and D act as terminal energy acceptors. From these results and previous analysis of the bicylindrical core of Synechococcus 6301 phycobilisomes [14,15] it is proposed that the two cylinders of the Synechocystis 6701 core, proximal to the thylakoid membrane, each have the composition ABCD, and that the distal cylinder has the composition A2B2.
mesh_terms: D002848:Chromatography, DEAE-Cellulose; D000458:Cyanobacteria / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D045342:Light-Harvesting Protein Complexes; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis; D045524:Phycobilisomes; D010798:Phycocyanin / Q000032:analysis; D010940:Plant Proteins / Q000032:analysis*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry
chemical_list: D045342:Light-Harvesting Protein Complexes; D010455:Peptides; D045524:Phycobilisomes; D010940:Plant Proteins; C002497:allophycocyanin; D010798:Phycocyanin