Identification of two structurally related proteins involved in proteolytic processing of precursors targeted to the chloroplast.
Two proteins of 145 and 143 kDa were identified in pea which co-purify with a chloroplast processing activity that cleaves the precursor for the major light-harvesting chlorophyll binding protein (preLHCP). Antiserum generated against the 145/143 kDa doublet recognizes only these two polypeptides in a chloroplast soluble extract. In immunodepletion experiments the antiserum removed the doublet, and there was a concomitant loss of cleavage of preLHCP as well as of precursors for the small subunit of Rubisco and the acyl carrier protein. The 145 and 143 kDa proteins co-eluted in parallel with the peak of processing activity during all fractionation procedures, but they were not detectable as a homo- or heterodimeric complex. The 145 and 143 kDa proteins were used separately to affinity purify immunoglobulins; each preparation recognized both polypeptides, indicating that they are antigenically related. Wheat chloroplasts contain a soluble species similar in size to the 145/143 kDa doublet.
Oblong
J E
JE
Department of Molecular Genetics and Cell Biology, University of Chicago, IL 60637.
Lamppa
G K
GK
D001692:Biological Transport; D015153:Blotting, Western; D002499:Centrifugation, Density Gradient; D002736:Chloroplasts / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes; D007887:Fabaceae / Q000737:chemistry; D006868:Hydrolysis; D008970:Molecular Weight; D010940:Plant Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D010946:Plants, Medicinal; D011487:Protein Conformation; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D013379:Substrate Specificity; D014908:Triticum / Q000737:chemistry
D000939:Epitopes; D010940:Plant Proteins; D011498:Protein Precursors