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. 1989 Jan;89(1):238–243. doi: 10.1104/pp.89.1.238

Chloroplast Thylakoid Protein Phosphatase Is a Membrane Surface-Associated Activity 1

Gongqin Sun 1, Doreen Bailey 1, Michael W Jones 1, John Markwell 1
PMCID: PMC1055825  PMID: 16666520

Abstract

Chloroplast thylakoid protein phosphatase activity was measured using 32P-labeled histone as an exogenous substrate and an assay of the 32Pi released involving formation of a phosphomolybdate complex and organic extraction. The activity was liberated from wheat (Triticum aestivum) thylakoids by washing the membranes in NaCl-containing solutions followed by centrifugation. The liberated phosphatase activity had a pH optimum of approximately 6.75, was inhibited by addition of 10 millimolar EDTA or EGTA, and was stimulated by addition of millimolar amounts of dithiothreitol, magnesium, manganese, or calcium ions. The rate of thylakoid protein dephosphorylation was decreased following liberation of a portion of the protein phosphatase activity and was increased by addition of salt-liberated phosphatase fraction. These results suggest that at least a portion of wheat thylakoid protein phosphatase is a peripheral, rather than an integral, membrane protein.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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