You are not currently logged in.
Access JSTOR through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Molecular Evolution of Biomembranes: Structural Equivalents and Phylogenetic Precursors of Sterols
Michel Rohmer, Pierrette Bouvier and Guy Ourisson
Proceedings of the National Academy of Sciences of the United States of America
Vol. 76, No. 2 (Feb., 1979), pp. 847-851
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/69167
Page Count: 5
You can always find the topics here!Topics: Sterols, Squalene, Prokaryotes, Lipids, Molecular evolution, Eukaryotic cells, Biosynthesis, Carotenoids, Acetobacter, Epoxy compounds
Were these topics helpful?See somethings inaccurate? Let us know!
Select the topics that are inaccurate.
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
Derivatives of one triterpene family, the hopane family, are widely distributed in prokaryotes; they may be localized in membranes, playing there the same role as sterols play in eukaryotes, as a result of their similar size, rigidity, and amphiphilic character. Their biosynthesis embodies many primitive features compared to that of sterols and could have evolved toward the latter once aerobic conditions had been established. Membrane reinforcement appears to be achieved in other prokaryotes by other mechanisms, involving either ≈ 44- angstrom -long rigid hydrocarbon chains terminated by one polar group acting like a peg through the double-layer or similar chains terminated by two polar groups acting like tie-bars across the membrane. These inserts can be tetraterpenes (e.g., carotenoids). The biophysical function of membrane optimizers appears to have evolved toward sterols by changes limited to only a few enzymatic steps of the same fundamental biosynthetic processes.
Proceedings of the National Academy of Sciences of the United States of America © 1979 National Academy of Sciences