Membranes of Rhodopseudomonas sphaeroides. VI. Isolation of a fraction enriched in newly synthesized bacteriochlorophyll alpha-protein complexes.
Radioactivity eventually destined for the chromatophore membrane of Rhodopseudomonas sphaeroides was shown in pulse-chase studies to appear first in a distinct pigmented fraction. The material formed an upper pigmented band which sedimented more slowly than chromatophores when cell-free extracts were subjected directly to rate-zone sedimentation on sucrose density gradients. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the purified fraction contained polypeptide bands of the same mobility as light-harvesting bacteriochlorophyll alpha and reaction center-associated protein components of chromatophores; these were superimposed upon cytoplasmic membrane polypeptides. The pulse-chase relation was confined mainly to the polypeptide components of these pigment-protein complexes. It is suggested that the isolated fraction may be derived from sites at which new membrane invagination is initiated.
D020130:Bacterial Chromatophores / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis*; D001429:Bacteriochlorophylls / Q000096:biosynthesis*; D002462:Cell Membrane / Q000378:metabolism; D002701:Chloramphenicol / Q000494:pharmacology; D002734:Chlorophyll / Q000031:analogs & derivatives*; D007425:Intracellular Membranes / Q000378:metabolism*; D012242:Rhodobacter sphaeroides / Q000187:drug effects / Q000378:metabolism*; D013752:Tetracycline / Q000494:pharmacology
D001426:Bacterial Proteins; D001429:Bacteriochlorophylls; D002734:Chlorophyll; D002701:Chloramphenicol; D013752:Tetracycline