Freeze-fractured purple membrane particles: protein content

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Science  01 Jul 1977:
Vol. 197, Issue 4298, pp. 72-74
DOI: 10.1126/science.867052


Optical diffraction and image reconstruction can be used to correlate the electron microscope image of the biological membrane with its electron density projection. Such correlation shows that a single purple membrane particle contains 9 to 12 protein molecules--63 to 84 transmembrane alpha helices--a complexity two to ten times greater than that previously suggested for membrane particles.