Phosphorylation of Membrane-Located Proteins of Soybean: In Vitro Response of Purified Plasma Membranes to Auxin and Calcium
Isolated membranes of soybean incorpated 32P from γ-[32P]ATP in vitro. The incorporation was rapid and labeling was achieved in 10 s or less. When displayed on 10% sodium dodecylsulfate-polyacrylamide gels, several labeled protein bands were revealed (Morré et al., 1984). Incorporation into protein bands with apparent molecular weights of 45,000 and 50,000 as well as into total material insoluble in trichloroacetic acid was observed in the presence of auxin (2,4-dichlorophenoxyacetic acid = 2,4-D). Also, incorporation into a low molecular weight constituent was stimulated 2- to 3-fold by auxin in some experiments. The activity may be the result of protein kinases of the C-type since stimulation also was given by diglyceride plus calcium (Morré et al., 1984), constituents known to augment C-type kinases in other systems (Nishizuka, 1984).
KeywordsSucrose Polypeptide Dextran Inositol Polyethyleneglycol
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