Transbilayer organization of the chlorophyll-proteins of spinach thylakoids.
To investigate the transverse bilayer organization of the chlorophyll-proteins of the three intrinsic chlorophyll-protein complexes, the effects of proteolytic enzymes, and an antibody against the light-harvesting complex were compared using right-side-out and inside-out thylakoid vesicles. The vesicles were isolated by aqueous polymer phase partitioning following the fragmentation of spinach thylakoids by passage through a Yeda press. Both vesicle types were agglutinated by an antiserum specific for the light-harvesting complex, although proteolytic degradation of the complex occurred only in right-side-out vesicles. In addition, there are different antigenic sites for the light-harvesting complex on the inner and outer thylakoid surfaces. Polypeptides of the chlorophyll-alpha-protein complex of photosystem II were degraded by proteases at both membrane surfaces. We concluded that both these chlorophyll-protein complexes are membrane spanning and transversely asymmetric, but that the light-harvesting complex polypeptides accessible at the inner thylakoid surface are more resistant to proteolytic attack. In contrast, the main chlorophyll-containing polypeptide (Mr = 64 500) of photosystem I complex was resistant to proteolytic attack at both the outer and inner thylakoid surfaces.
D002734:Chlorophyll / Q000378:metabolism*; D002736:Chloroplasts / Q000276:immunology / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000276:immunology; D007163:Immunosorbent Techniques; D008051:Lipid Bilayers / Q000378:metabolism*; D010788:Photosynthesis; D010940:Plant Proteins / Q000378:metabolism*; D010944:Plants / Q000378:metabolism; D011402:Pronase; D014357:Trypsin
D000939:Epitopes; D008051:Lipid Bilayers; D010940:Plant Proteins; D002734:Chlorophyll; D014357:Trypsin; D011402:Pronase