Microtubule-based endoplasmic reticulum motility in Xenopus laevis: Activation of membrane-associated kinesin during development

Jon D. Lane, Victoria J. Allan

    Research output: Contribution to journalArticlepeer-review


    The endoplasmic reticulum (ER) in animal cells uses microtubule motor proteins to adopt and maintain its extended, reticular organization. Although the orientation of microtubules in many somatic cell types predicts that the ER should move toward microtubule plus ends, motor-dependent ER motility reconstituted in extracts of Xenopus laevis eggs is exclusively a minus end- directed, cytoplasmic dynein-driven process. We have used Xenopus egg, embryo, and somatic Xenopus tissue culture cell (XTC) extracts to study ER motility during embryonic development in Xenopus by video-enhanced differential interference contrast microscopy. Our results demonstrate that cytoplasmic dynein is the sole motor for microtubule-based ER motility throughout the early stages of development (up to at least the fifth embryonic interphase). When egg-derived ER membranes were incubated in somatic XTC cytosol, however, ER tubules moved in both directions along microtubules. Data from directionality assays suggest that plus end-directed ER tubule extensions contribute ~19% of the total microtubule-based ER motility under these conditions. In XTC extracts, the rate of ER tubule extensions toward microtubule plus ends is lower (~0.4 μm/s) than minus end-directed motility (~1.3 μm/s), and plus end-directed motility is eliminated by a function-blocking anti-conventional kinesin heavy chain antibody (SUK4). In addition, we provide evidence that the initiation of plus end-directed ER motility in somatic cytosol is likely to occur via activation of membrane-associated kinesin.
    Original languageEnglish
    Pages (from-to)1909-1922
    Number of pages13
    JournalMolecular Biology of the Cell
    Issue number6
    Publication statusPublished - Jun 1999


    Dive into the research topics of 'Microtubule-based endoplasmic reticulum motility in Xenopus laevis: Activation of membrane-associated kinesin during development'. Together they form a unique fingerprint.

    Cite this