Cell-free fusion of endocytic vesicles is regulated by phosphorylation

P. G. Woodman, D. I. Mundy, P. Cohen, G. Warren

    Research output: Contribution to journalArticlepeer-review

    53 Citations (Scopus)

    Abstract

    Okadaic acid and microcystin-LR, both potent inhibitors of protein phosphatases (PP), blocked vesicle fusion in a cell-free system. The effect of okadaic acid was reversed by the purified catalytic subunit of PP2A, but not PP1. Inhibition was gradual, required Mg-ATP, and was reduced by protein kinase inhibitors, indicating that it was mediated via protein phosphorylation. A candidate protein kinase would be cdc2 kinase, which normally is active in mitotic extracts and has been shown to inhibit endocytic vesicle fusion (Tuomikoski, T., M.-A. Felix, M. Doree, and J. Gruenberg. 1989. Nature (Lond.). 342:942-945). However, it would appear that cdc2 kinase is not responsible for inhibition by okadaic acid. When compared to cytosol prepared from mitotic cells, okadaic acid did not increase cdc2 kinase activity sufficiently to account for the inhibition. In addition, inhibition was maintained when cdc2 protein was depleted from cytosol.

    Original languageEnglish
    Pages (from-to)331-338
    Number of pages8
    JournalJournal of Cell Biology
    Volume116
    Issue number2
    DOIs
    Publication statusPublished - 15 Jan 1992

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