Stromal serine protein kinase activity in spinach chloroplasts
At least twelve /sup 32/P-labeled stromal proteins were detected by electrophoresis under denaturing conditions when intact chloroplasts were incubated with /sup 32/Pi, in the light but only three were detected in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) or in the dark. Incubation of isolated stroma with (gamma-/sup 32/P)ATP resulted in the preferential phosphorylation of one of them, a 70-kDa polypeptide, in serine residues. Thylakoid membranes in the dark promoted the phosphorylation of two additional stromal polypeptides of 55 and 40 kDa. Illumination during the phosphorylation of stroma in the presence of thylakoids stimulated severalfold the labeling of the 40-kDa polypeptide but not when DCMU was added. The protein kinase activity present in isolated stroma phosphorylated exogenous substrates like histone III, phosvitin, histone II, and casein with specific activities of 3, 1.8, 0.7, and 0.2 pmol X mg-1 X min-1. Histone III polypeptides were phosphorylated differently by stroma and by thylakoids in the dark. Moreover, histone III phosphorylated by thylakoids in the dark yielded a pattern of phosphopeptides after V8 protease treatment that was different from the pattern obtained when histone III was phosphorylated by stroma.
- Research Organization:
- Univ. Nacional de Rosario (Argentina)
- OSTI ID:
- 6409496
- Journal Information:
- Arch. Biochem. Biophys.; (United States), Vol. 2
- Country of Publication:
- United States
- Language:
- English
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CHLOROPLASTS
ENZYME ACTIVITY
PHOSPHOTRANSFERASES
ATP
HISTONES
MAGNESIUM
PHOSPHORUS 32
PHOSPHORYLATION
PLANTS
PROTEIN DENATURATION
SPINACH
TRACER TECHNIQUES
ALKALINE EARTH METALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CELL CONSTITUENTS
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ELEMENTS
ENZYMES
FOOD
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
METALS
NUCLEI
NUCLEOPROTEINS
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PROTEINS
RADIOISOTOPES
TRANSFERASES
VEGETABLES
550201* - Biochemistry- Tracer Techniques