Author
S. J. Wojcik
Bio: S. J. Wojcik is an academic researcher from University of Auckland. The author has contributed to research in topics: Phosphorylation & Kinase. The author has an hindex of 1, co-authored 1 publications receiving 48 citations.
Topics: Phosphorylation, Kinase, Kinetin, Adenosine, Zeatin
Papers
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TL;DR: Protein phosphorylation in vitro was not affected by adenosine 3':5'-cyclic monophosphate, indol-3-ylacetic acid or gibberellic acid, and N(9)-unsubstituted purines, among which the known cytokinins were the most effective inhibitors.
Abstract: Kinetin stimulated phosphorylation of protein in floated Chinese-cabbage leaf discs, but inhibited protein phosphorylation in nuclei+chloroplast extracts from Chinese-cabbage or tobacco leaves. Kinetin also inhibited protein phosphorylation in isolated tobacco nuclei or nuclei from carrot secondary-phloem tissue. Purified Chinese-cabbage leaf ribosomes exhibited protein kinase activity which was inhibited by kinetin and zeatin. The ribosome-associated kinase responded to kinetin and zeatin differently from that associated with nuclei+chloroplast preparations. Protein phosphorylation in vitro was not affected by adenosine 3′:5′-cyclic monophosphate, indol-3-ylacetic acid or gibberellic acid. It was only inhibited by N 9 -unsubstituted purines, among which the known cytokinins were the most effective inhibitors. The results are discussed in relation to possible similarities between the effects of cytokinins in plant tissues and the effects of adenosine 3′:5′-cyclic monophosphate in animal tissues. Both compounds appear to modify the activity of protein kinases and both affect many different cellular processes.
48 citations
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TL;DR: Protein phosphorylation is a reversible, energy-dependent membrane modification, but it differs from the other changes in that it takes the form of a specific chemical reaction involving certain identifiable chloroplast membrane polypeptides.
Abstract: ILLUMINATION of chloroplast thylakoids leads to the formation of the so-called high energy state of the membrane1–3. The establishment of this state is accompanied by several structural changes within the membrane, including a conformational change in the coupling factor4, increased accessibility of photosystem II to the chemical probe p-diazonium benzene sulphonate5, and a reduction in the thickness of the partition between stacked thylakoids6. I describe here a rather different type of structural change that has not previously been reported for chloroplast membranes—protein phosphorylation. Like the above changes, protein phosphorylation is a reversible, energy-dependent membrane modification, but it differs from the other changes in that it takes the form of a specific chemical reaction involving certain identifiable chloroplast membrane polypeptides. The most conspicuous of these polypeptides is the light-harvesting chlorophyll a/b binding protein, the most abundant thylakoid polypeptide7.
383 citations
TL;DR: To classify protein kinases from 25 plant species and to assess their evolutionary history in conjunction with consideration of their molecular functions, which shows a large variation in kinome size is mainly due to the expansion and contraction of a few families.
Abstract: Eukaryotic protein kinases belong to a large superfamily with hundreds to thousands of copies and are components of essentially all cellular functions. The goals of this study are to classify prote...
257 citations
TL;DR: A growing body of evidence showing a variety of plant responses to small oligosaccharides strongly suggests that the diversity of chemical messages used by plants to react to external signals and/or to integrate their functions at the whole plant level is far greater than that corresponding to the 'classical' plant hormones.
75 citations
TL;DR: A phospholipid-stimulatedprotein kinase has been demonstrated in plant extracts which is similar to protein kinase C in its behaviour on a DE-52 cellulose column, its substrate specificity and its calcium dependence, but the lack of specific phorbol ester binding by the enzyme fractions makes a complete identity with protein kinases C doubtful.
75 citations
TL;DR: The proteolytic peptide maps, however, were clearly distinguishable in autoradiograms, suggesting that different serine residues were phosphorylated by ChlPK1 and Chl PK2.
73 citations