Abstract
A membrane-bound protein kinase, which catalyses the phosphorylation of endogenous substrates, has been isolated from homogenates of Jerusalem artichoke rhizome tissues by differential and discontinuous sucrose-gradient centrifugation. Electron microscopic analysis revealed that the membrane fractions showing endogenous protein kinase activity contained vesicles of various sizes and that most of these structures were stained by phosphotungstic acid/chromic acid, a stain that is known to be almost specific for plant plasma membranes. The enzyme has an almost absolute requirement for Mg 2+. It is unaffected by cyclic AMP, indoleacetic acid, gibberellic acid and fusicoccin. Adenosine and its cytokinin derivative isopentenyladenosine were inhibitory. When acidic (casein and phosvitin) or basic (histone and protamine) proteins were used as exogenous substrates only acidic proteins are phosphorylated by the enzyme. The endogenous phosphorylated substrates have been characterized by SDS-polyacrylamide gel electrophoresis.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
