A purified 124-kDa oat phytochrome does not possess a protein kinase activity.
The presence of protein kinase activity in the purified phytochrome preparations [Wong, et al. (1986) J. Biol. Chem. 261, 12089-12097] has been re-examined. The phytochrome preparations having SAR (specific absorbance ratio, A668/A280 for the Pr form as a measure of phytochrome purity) values of greater than 0.95 were homogeneous on SDS gel, but could be further purified to a SAR value of 1.07 by repeated gel filtrations on a Bio-Gel A-0.5 m column. The protein kinase activity remained in the phytochrome preparations having SAR values less than 1.05, but it became undetectable in the phytochrome preparation with a SAR value of 1.07. Two dimensional gel electrophoresis of the phytochrome preparation (SAR, 0.89) showed that a phytochrome band with pl 5.8 had no kinase activity. Phosphorylating activity of the protein kinase was enhanced to some extent by polycations, polylysine and histone. Phytochrome served as a good substrate for this enzyme. The present data indicate that phytochrome has no intrinsic protein kinase activity, but a protein kinase is present in highly purified phytochrome preparations.
Kim
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IS
Bai
U
U
Song
P S
PS
D002523:Edible Grain / Q000378:metabolism; D008970:Molecular Weight; D010834:Phytochrome / Q000302:isolation & purification / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*
D010940:Plant Proteins; D010834:Phytochrome; D011494:Protein Kinases