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Updated: Aug 16, 2026

A New Approach for the Comparative Analysis of Multiprotein Complexes Based on 15N Metabolic Labeling and Quantitative Mass Spectrometry
Published on: March 13, 2014
Chloroplast phosphoproteins. Phosphorylation of polypeptides of the light-harvesting chlorophyll protein complex
Abstract:
When isolated, intact chloroplasts of pea (Pisum sativum) are incubated in the light with [32P]-orthophosphate, isotope is incorporated into several polypeptides. Among the most conspicuous phosphoproteins are two which form a very closely spaced doublet on dodecyl sulphate/polyacrylamide gels and co-electrophorese with the major polypeptide component of the light-harvesting chlorophyll a/b binding complex. Like the light-harvesting polypeptide, the phosphoprotein doublet is bound to thylakoids, sediments with the heavy particles released from thylakoids after digitonin treatment, is soluble in chloroform/methanol and has an apparent molecular weight of about 26 000. The doublet also appears in the highly purified light-harvesting chlorophyll a/b binding complex isolated from thylakoids by hydrosylapatite chromatography. I conclude that two polypeptide components of the complex are phosphorylated. One of these components may be the major light-harvesting chlorophyll a/b binding protein.
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