The 64,000 MW chloroplast protein kinase is a loosely bound thylakoid protein
- Memphis State Univ., TN (United States)
- Brookhaven National Lab., Upton, NY (United States)
A 64 kDa phosphoprotein copurifies with histone kinase activity in detergent extract of thylakoid membranes and has been provisionally identified as the kinase (e.g. JBC 261 14062). The authors have prepared antibodies to this protein. As measured by western blotting, release of the kinase from thylakoids correlates with loss of kinase activity and preceeds solubilization of the bulk of the cytochrome b/f complex. Although treatment with NaBr, KI and urea did not release the protein, some was lost during NaOH washes and essentially all of it appeared in the aqueous fraction during the phase partitioning with Triton X-114. Although it dissociates with relative ease from thylakoids, fractionation experiments indicate that the 64kDa is in fact a membrane protein and not an adventitiously bound stromal enzyme. Measured on the same 13% acrylamide gel, the kinase's molecular weight is 5 to 7 kDa smaller than that of the major stromal protein labeled with {sup 32}P-ATP. Unlike the stromal protein, the extent of labeling of the 64 kDa was unchanged by the subsequent chases with non-radioactive ATP. They conclude that while the 64 kDa protein may be a peripheral membrane protein, it is not a contaminating stromal enzyme with a phosphoenzyme intermediate like phosphoglucomutase. It is very likely that it is the kinase.
- OSTI ID:
- 5515971
- Report Number(s):
- CONF-9107184--
- Journal Information:
- Plant Physiology, Supplement; (United States), Journal Name: Plant Physiology, Supplement; (United States) Vol. 96:1; ISSN PPYSA; ISSN 0079-2241
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ATP
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
DAYS LIVING RADIOISOTOPES
ENZYME ACTIVITY
ENZYMES
HYDROGEN COMPOUNDS
HYDROXIDES
ISOTOPES
KINETICS
LIGHT NUCLEI
MEMBRANE PROTEINS
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
SODIUM COMPOUNDS
SODIUM HYDROXIDES
THYLAKOID MEMBRANE PROTEINS
TRANSFERASES