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Examining the Conformational Dynamics of Membrane Proteins in situ with Site-directed Fluorescence Labeling
11:55

Examining the Conformational Dynamics of Membrane Proteins in situ with Site-directed Fluorescence Labeling

Published on: May 29, 2011

Are there knobs on energy transducing membranes in situ?

W W Wainio

    Journal of Ultrastructure Research
    |December 1, 1985
    PubMed

    Insights

    Mitochondrial inner membrane spheres, often seen in fragmented preparations, are likely artifacts from sample preparation or staining. These structures are rarely observed in intact cells, suggesting they are not inherent features of the mitochondria.

    Area of Science:

    • Cell Biology
    • Mitochondrial Research
    • Electron Microscopy

    Background:

    • The mitochondrial inner membrane contains projections often described as globules or knob-on-stalks.
    • These structures are frequently observed in negatively stained preparations of submitochondrial particles.

    Purpose of the Study:

    • To investigate whether the observed projections on the mitochondrial inner membrane are true structures or artifacts.
    • To determine the influence of sample preparation and staining techniques on the visualization of these mitochondrial features.

    Main Methods:

    • Comparative analysis of mitochondrial structures using sectioned and freeze-fractured preparations of intact cells and isolated mitochondria.
    • Examination of fragmented preparations, particularly those subjected to negative staining with phosphotungstate.

    Main Results:

    • Externalized spheres on mitochondrial membranes are rarely observed in sectioned or freeze-fractured preparations of intact cells or mitochondria.
    • These spherical projections are consistently observed in fragmented preparations, especially when negatively stained with phosphotungstate.

    Conclusions:

    • The frequently observed projections on the matrix side of the mitochondrial inner membrane are likely artifacts.
    • Artifacts arise from the preparation and/or staining methods used for submitochondrial particles or mitochondria.
    • The visualization of these structures is highly dependent on the integrity of the preparation and the staining technique employed.

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