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Journal ArticleDOI

Structure of purple membrane from halobacterium halobium: recording, measurement and evaluation of electron micrographs at 3.5 Å resolution

01 Jan 1986-Ultramicroscopy (North-Holland)-Vol. 19, Iss: 2, pp 147-178
TL;DR: In this article, the strength of the very weak high-resolution Fourier components of the image of a two-dimensional crystal was determined using real space correlation analysis, and the amplitude and phase information was extracted from the distortion-corrected image of the crystal.
About: This article is published in Ultramicroscopy.The article was published on 1986-01-01. It has received 694 citations till now. The article focuses on the topics: Contrast transfer function & Resolution (electron density).
Citations
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Journal ArticleDOI
TL;DR: A complete atomic model for bacteriorhodopsin between amino acid residues 8 and 225 has been built and suggests that pK changes in the Schiff base must act as the means by which light energy is converted into proton pumping pressure in the channel.

2,772 citations

Journal ArticleDOI
TL;DR: EMAN (Electron Micrograph ANalysis), a software package for performing semiautomated single-particle reconstructions from transmission electron micrographs, was written from scratch in C++ and is provided free of charge on the Web site.

2,551 citations

Journal ArticleDOI
17 Feb 1994-Nature
TL;DR: The structure of the light-harvesting chlorophyll a/b–protein complex, an integral membrane protein, has been determined at 3.4 Å resolution by electron crystallography of two-dimensional crystals.
Abstract: The structure of the light-harvesting chlorophyll a/b-protein complex, an integral membrane protein, has been determined at 3.4 A resolution by electron crystallography of two-dimensional crystals. Two of the three membrane-spanning alpha-helices are held together by ion pairs formed by charged residues that also serve as chlorophyll ligands. In the centre of the complex, chlorophyll a is in close contact with chlorophyll b for rapid energy transfer, and with two carotenoids that prevent the formation of toxic singlet oxygen.

1,801 citations

Journal ArticleDOI
05 Oct 2000-Nature
TL;DR: An atomic model of human red cell AQP1 is described, providing a possible molecular explanation to a longstanding puzzle in physiology—how membranes can be freely permeable to water but impermeable to protons.
Abstract: Human red cell AQP1 is the first functionally defined member of the aquaporin family of membrane water channels. Here we describe an atomic model of AQP1 at 3.8A resolution from electron crystallographic data. Multiple highly conserved amino-acid residues stabilize the novel fold of AQP1. The aqueous pathway is lined with conserved hydrophobic residues that permit rapid water transport, whereas the water selectivity is due to a constriction of the pore diameter to about 3 A over a span of one residue. The atomic model provides a possible molecular explanation to a longstanding puzzle in physiology-how membranes can be freely permeable to water but impermeable to protons.

1,662 citations

Journal ArticleDOI
TL;DR: Two computer programs are presented, CTFFIND3 and CTFTILT, which determine defocus parameters from images of untilted specimens, as well as defocus and tilt parameters from image of tilted specimens, respectively, using a simple algorithm.

1,480 citations


Cites background or methods from "Structure of purple membrane from h..."

  • ...The defocus parameters can also be determined by a least-squares fit between the calculated CTF and square root of the observed power spectrum (Frank, 1972) or between the square of the calculated CTF and the power spectrum (Henderson et al., 1986)....

    [...]

  • ...The oscillations visible in the power spectrum of an electron micrograph (Thon rings; Thon, 1966) have been used before to determine defocus parameters for untilted specimens (for example, Conway and Steven, 1999; Frank, 1972; Henderson et al., 1986; Ludtke et al., 1999; Morgan et al., 1995; Tani et al., 1996; Zhu et al., 1997), and to obtain tilt information (Henderson and Unwin, 1975; van Heel et al....

    [...]

References
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Journal ArticleDOI
04 Sep 1975-Nature
TL;DR: A 7-Å resolution map of the purple membrane has been obtained by electron microscopy of tilted, unstained specimens and shows that Lipid bilayer regions fill the spaces between the protein molecules.
Abstract: A 7-A resolution map of the purple membrane has been obtained by electron microscopy of tilted, unstained specimens. The protein in the membrane contains seven, closely packed, alpha-helical segments which extend roughly perpendicular to the plane of the membrane for most of its width. Lipid bilayer regions fill the spaces between the protein molecules.

2,114 citations

Journal ArticleDOI
29 Sep 1971-Nature
TL;DR: It is shown that the purple colour is due to retinal bound to an opsin-like protein, the only protein present in this membrane fragment, which has been isolated in relatively pure form from Halobacterium halobium.
Abstract: HALOPHILIC bacteria require high concentrations of sodium chloride and lower concentrations of KCl and MgCl2 for growth. The cell membrane dissociates into fragments of varying size when the salt is removed1. One characteristic fragment—termed the “purple membrane” because of its characteristic deep purple colour—has been isolated in relatively pure form from Halobacterium halobium2. We can now show that the purple colour is due to retinal bound to an opsin-like protein, the only protein present in this membrane fragment (see also ref. 3).

1,849 citations

Journal ArticleDOI
TL;DR: The projected structures of two unstained periodic biological specimens, the purple membrane and catalase, have been determined by electron microscopy to resolutions of 7 A and 9 A, respectively.

1,045 citations

Journal ArticleDOI
TL;DR: An adaptation of the ‘correlation averaging’ method is described which allows reliable and almost fully automatic image averaging in the case of near‐periodic structures notwithstanding the presence of substantial crystal imperfections.
Abstract: An adaptation of the 'correlation averaging' method is described which allows reliable and almost fully automatic image averaging in the case of near-periodic structures notwithstanding the presence of substantial crystal imperfections; methods for assessing resolution and symmetry without reliance on crystallinity are also discussed. Electron micrographs of negatively stained and rotary shadowed preparations of the HPI-layer protein from the cell envelope of Micrococcus radiodurans have been averaged using the method, and the projected structure is described to a resolution of about 1.9 nm.

837 citations