Abstract
Ribulose bisphosphate carboxylase consists of cytoplasmically synthesized "small" subunits and chloroplast-synthesized "large" subunits. Large subunits of ribulose bisphosphate carboxylase synthesized in vivo or in organello can be recovered from intact chloroplasts in the form of two different complexes with sedimentation coefficients of 7S and 29S. About one-third to one-half of the large subunits synthesized in isolated chloroplasts are found in the 7S complex, the remainder being found in the 29S complex. Upon prolonged illumination of the chloroplasts, newly synthesized large subunits accumulate in the 18S ribulose bisphosphate carboxylase molecule and disappear from both the 7S and the 29S large subunit complexes. The 29S complex undergoes an in vitro dissociation reaction and is not as stable as ribulose bisphosphate carboxylase. The data indicate that (a) the 7S large subunit complex is a chloroplast product, the (b) the 29S large subunit complex is labeled in vivo, that (c) each of these two complexes can account quantitatively for all the large subunits assembled into RuBPCase in organello, and that (d) excess large subunits are degraded in chloroplasts.
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Selected References
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- Bennett J. Biosynthesis of the light-harvesting chlorophyll a/b protein. Polypeptide turnover in darkness. Eur J Biochem. 1981 Aug;118(1):61–70. doi: 10.1111/j.1432-1033.1981.tb05486.x. [DOI] [PubMed] [Google Scholar]
- Chua N. H., Schmidt G. W. Post-translational transport into intact chloroplasts of a precursor to the small subunit of ribulose-1,5-bisphosphate carboxylase. Proc Natl Acad Sci U S A. 1978 Dec;75(12):6110–6114. doi: 10.1073/pnas.75.12.6110. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Morgenthaler J. J., Price C. A. Photosynthetic activity of spinach chloroplasts after isopycnic centrifugation in gradients of silica. Plant Physiol. 1974 Oct;54(4):532–534. doi: 10.1104/pp.54.4.532. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Smith M. A., Criddle R. S., Peterson L., Huffaker R. C. Synthesis and assembly of ribulosebisphosphate carboxylase enzyme during greening of barley plants. Arch Biochem Biophys. 1974 Dec;165(2):494–504. doi: 10.1016/0003-9861(74)90275-6. [DOI] [PubMed] [Google Scholar]