Probing in vitro translation products with monoclonal antibodies to chlorophyll a/b-binding proteins of barley thylakoids.
The polypeptides of the barley light-harvesting protein of photosystem I (LHCI) share certain epitopes. At least two of these common epitopes are present in chlorophyll a/b-protein 1 (Chla/b-P1 = CP29), as shown by cross-reacting monoclonal antibodies (14). These antibodies were employed for immunological identification of polypeptides translated in vitro in an mRNA-dependent cell-free rabbit reticulocyte lysate. The monoclonal antibody CMpLHCI:2 precipitated only one polypeptide of molecular weight 28 kD from in vitro translates primed with polyA+ RNA. No 28 kD precipitation band was found, if this antibody was mixed with a PSI-200 preparation before it was added to the translate. The translational capacity of the LHCI transcripts isolated from 12 hours greened barley was much higher than those isolated from 6 hours greened barley. Transcripts for LHCI polypeptides were also found among the polyA+ RNA of the mutant viridis-k23, which is devoid of LHCI polypeptides in its thylakoid membranes. The monoclonal antibody CMpCh1a/b-P1:1 precipitated a polypeptide of molecular weight 31 kD from in vitro translates primed with polyA+ RNA. Thus, the cross-reactivity the two antibodies show with the mature proteins is not found when the antibodies are reacted with the precursor proteins.
Høyer-Hansen
G
G
Department of Physiology, Carlsberg Laboratory, Copenhagen Valby.
Hønberg
L S
LS
Bassi
R
R
D000911:Antibodies, Monoclonal / Q000276:immunology*; D002734:Chlorophyll / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D003429:Cross Reactions; D002523:Edible Grain / Q000032:analysis*; D000939:Epitopes / Q000276:immunology; D001467:Hordeum / Q000032:analysis*; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D011061:Poly A / Q000235:genetics; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics
D000911:Antibodies, Monoclonal; D000939:Epitopes; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins; D012333:RNA, Messenger; D002734:Chlorophyll; D011061:Poly A