Very little is known about the molecular events triggering differentiated cells to re-enter the cell cycle. We have investigated the possible role of tyrosine phosphorylation in this process with hypocotyl explants of Arabidopsis thaliana. Phytohormone-stimulated cell cycle reactivation in hypocotyls was accompanied by tyrosine phosphorylation of several proteins. Such regulation of the tyrosine phosphorylation in these proteins was not observed in a callus-formation-deficient mutant, srd2, a result which suggests that the induction of tyrosine phosphorylation occurs as a specific event in callus cell proliferation. The promoter activity of cyclin-dependent kinase, CDKA;1, was also examined in phytohormone-stimulated hypocotyls. This study highlighted that protein tyrosine phosphorylation may play an important regulatory role in phytohormone-stimulated cell proliferation.
Keywords: Keywords: Cell proliferation — Cyclin-dependent kinase — Tyrosine phosphorylation.; Abbreviations: 2,4-D, 2,4-dichlorophenoxyacetic acid; PTKs, protein tyrosine kinases; PTPs, protein tyrosine phosphatases.
Journal Article. 3522 words. Illustrated.
Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry
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